diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c2065bc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..1218db4
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,19 @@
+build-docker:
+	docker build -f distribution/docker/Dockerfile --build-arg JAR_FILE=build/libs/\*.jar -t lindar/bingoticketgenerator-apalfi:0.0.1-SNAPSHOT .
+
+build-gradle:
+	./gradlew clean build
+
+build: build-gradle build-docker
+
+run-docker:
+	docker run -p 8080:8080 lindar/bingoticketgenerator-apalfi:0.0.1-SNAPSHOT
+
+boot-run:
+	./gradlew bootRun
+
+run-tests:
+	./gradlew test --tests "com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator*"
+
+run-perf-tests:
+	./gradlew test --tests 'com.attilapalfi.lindar.bingoticketgenerator.performancetest*'
diff --git a/README.md b/README.md
index 7855e05..a3e0b9b 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,56 @@
+
+## System Requirements
+- Java 17, gradle
+- Docker
+
+## Build & Run
+Use the Makefile to execute build & run commands.
+
+To build with gradle and docker:
+```shell
+make build
+```
+
+To run the docker container:
+```shell
+make run-docker
+```
+If the container started, the ticket generator endpoint is available at:
+
+### [http://localhost:8080/bingo/newStrips](http://localhost:8080/bingo/newStrips)
+
+To run tests or performance tests:
+```shell
+make run-tests
+make run-perf-tests
+```
+
+## Implementation Details
+- `-1` means `Blank` space in the ticket
+- the core part of the algorithm is in `AbstractTicketGenerator`
+  - it iterates through the spaces of the tickets row by row and based on a set of rules it places the blanks and numbers
+- time complexity of the algorithm is `O(n)` with some amortized time, where `n` is the total number of spaces in the 6 tickets
+  - the algorithm is hard to scale though. it was specifically implemented to generate 3x9 tickets in batches of 6
+- array lists are initialized in the `ArrayBasedTicketGenerator` to keep track of the state of the ticket generator
+  - these array lists are maybe not optimal: removing an element has `O(n)` time complexity
+  - it is possible to create another subclass for `AbstractTicketGenerator` which uses another approach
+    - e.g. instead of array lists, shuffled linked lists. removing from LL: `O(1)`, shuffling during init: `O(nlogn)`
+  - altough these are very small array lists: `n` is usually smaller than 20
+- an error checking is part of the algorithm, because in very rare cases an invalid ticket is generated. 
+As soon as it's detected, the algorithm drops it and starts creating a new one. 
+  - luckily this does not have a performance impact because it's so rare
+
+## Performance
+On my machine the performance test executed with these results:
+
+`Generated 10.000 strips in 487 ms.`
+
+And with 16 threads:
+
+`Generated 100.000 strips in parallel in 1602 ms.`
+
+------
+Original content:
 # Ticket Generator Challenge
 
 A small challenge that involves building a [Bingo 90](https://en.wikipedia.org/wiki/Bingo_(United_Kingdom)) ticket generator.
@@ -19,3 +72,4 @@ A small challenge that involves building a [Bingo 90](https://en.wikipedia.org/w
 
 Try to also think about the performance aspects of your solution. How long does it take to generate 10k strips? 
 The recommended time is less than 1s (with a lightweight random implementation)
+
diff --git a/build.gradle.kts b/build.gradle.kts
new file mode 100644
index 0000000..929a851
--- /dev/null
+++ b/build.gradle.kts
@@ -0,0 +1,35 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("org.springframework.boot") version "2.7.1"
+	id("io.spring.dependency-management") version "1.0.11.RELEASE"
+	kotlin("jvm") version "1.6.21"
+	kotlin("plugin.spring") version "1.6.21"
+}
+
+group = "com.attilapalfi.lindar"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_17
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "17"
+	}
+}
+
+tasks.withType<Test> {
+	useJUnitPlatform()
+}
diff --git a/distribution/docker/Dockerfile b/distribution/docker/Dockerfile
new file mode 100644
index 0000000..ec52d9e
--- /dev/null
+++ b/distribution/docker/Dockerfile
@@ -0,0 +1,4 @@
+FROM openjdk:17-alpine
+ARG JAR_FILE=target/*.jar
+COPY ${JAR_FILE} app.jar
+ENTRYPOINT ["java","-jar","/app.jar"]
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..41d9927
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..00e33ed
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100644
index 0000000..1b6c787
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..107acd3
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle.kts b/settings.gradle.kts
new file mode 100644
index 0000000..1283238
--- /dev/null
+++ b/settings.gradle.kts
@@ -0,0 +1 @@
+rootProject.name = "bingo-ticket-generator"
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/BingoTicketGeneratorApplication.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/BingoTicketGeneratorApplication.kt
new file mode 100644
index 0000000..c0313dc
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/BingoTicketGeneratorApplication.kt
@@ -0,0 +1,11 @@
+package com.attilapalfi.lindar.bingoticketgenerator
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class BingoTicketGeneratorApplication
+
+fun main(args: Array<String>) {
+	runApplication<BingoTicketGeneratorApplication>(*args)
+}
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/DeterministicRandomProvider.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/DeterministicRandomProvider.kt
new file mode 100644
index 0000000..aadd29d
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/DeterministicRandomProvider.kt
@@ -0,0 +1,10 @@
+package com.attilapalfi.lindar.bingoticketgenerator.random
+
+import org.springframework.stereotype.Component
+
+@Component
+class DeterministicRandomProvider : RandomProvider {
+    override fun nextInt(until: Int): Int {
+        return 0
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/RandomProvider.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/RandomProvider.kt
new file mode 100644
index 0000000..4af43b1
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/RandomProvider.kt
@@ -0,0 +1,5 @@
+package com.attilapalfi.lindar.bingoticketgenerator.random
+
+interface RandomProvider {
+    fun nextInt(until: Int): Int
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/SimpleRandomProvider.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/SimpleRandomProvider.kt
new file mode 100644
index 0000000..495b0c9
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/random/SimpleRandomProvider.kt
@@ -0,0 +1,18 @@
+package com.attilapalfi.lindar.bingoticketgenerator.random
+
+import org.springframework.stereotype.Component
+import kotlin.random.Random
+
+@Component
+class SimpleRandomProvider : RandomProvider {
+
+    private val random = Random(System.currentTimeMillis())
+
+    override fun nextInt(until: Int): Int {
+        return if (until == 0) {
+            0
+        } else {
+            random.nextInt(until)
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/AbstractTicketGenerator.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/AbstractTicketGenerator.kt
new file mode 100644
index 0000000..9aafa70
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/AbstractTicketGenerator.kt
@@ -0,0 +1,196 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+import com.attilapalfi.lindar.bingoticketgenerator.random.RandomProvider
+import kotlin.math.min
+
+const val BLANK = -1
+const val TICKETS = 6
+const val ROWS = 3
+const val NUMBERS_IN_ROW = 5
+const val BLANKS_IN_ROW = 4
+const val COLUMNS = NUMBERS_IN_ROW + BLANKS_IN_ROW
+const val SPACES_IN_TICKET = COLUMNS * ROWS
+
+const val NUMBERS_IN_FIRST_COLUMN = 9
+const val NUMBERS_IN_MIDDLE_COLUMNS = 10
+const val NUMBERS_IN_LAST_COLUMN = 11
+const val TOTAL_ROWS_IN_STRIP_OF_SIX = 18
+
+sealed class AbstractTicketGenerator(protected val randomProvider: RandomProvider) : TicketGenerator {
+    protected lateinit var sixTickets: SixTickets
+    protected lateinit var remainingBlanksInColumn: MutableMap<Int, Int>
+    private lateinit var remainingNumbersInRow: MutableMap<Int, Int>
+
+
+    override fun generateTickets(): SixTickets {
+        initNewStripOfSix()
+        loop@ for (ticket in 0 until TICKETS) {
+            if (sixTickets.invalid) break@loop
+            for (row in 0 until ROWS) {
+                if (sixTickets.invalid) break@loop
+                fillRow(ticket, row)
+            }
+        }
+        return returnOrRegenerateIfInvalid()
+    }
+
+    private fun fillRow(ticket: Int, row: Int) {
+        val mustBlankSpaces = HashSet<Int>()
+        val mustNumberSpaces = HashSet<Int>()
+        val columnIndices = Array(COLUMNS) { it }.toMutableList().shuffled()
+        fillWithMandatoryBlanksAndNumbers(columnIndices, ticket, row, mustBlankSpaces, mustNumberSpaces)
+        fillTheRestWithBlanksAndNumbers(columnIndices, mustBlankSpaces, mustNumberSpaces, ticket, row)
+        setInvalidIfNeeded(ticket, row)
+    }
+
+    private fun fillWithMandatoryBlanksAndNumbers(
+        columnIndices: List<Int>,
+        ticket: Int,
+        row: Int,
+        mustBlankSpaces: HashSet<Int>,
+        mustNumberSpaces: HashSet<Int>
+    ) {
+        var columnIterationsLeft = 8
+        columnIndices.forEachIndexed { columnIterator, column ->
+            if (canBeBlank(ticket, row, column) && mustBeBlank(
+                    ticket,
+                    row,
+                    column,
+                    columnIterator,
+                    columnIndices
+                )
+            ) {
+                mustBlankSpaces.add(column)
+                addBlank(ticket, row, column)
+            } else if (mustBeNumber(ticket, row, column, columnIterationsLeft)) {
+                mustNumberSpaces.add(column)
+                addNumber(ticket, row, column)
+            }
+            columnIterationsLeft--
+        }
+    }
+
+    private fun fillTheRestWithBlanksAndNumbers(
+        columnIndices: List<Int>,
+        mustBlankSpaces: HashSet<Int>,
+        mustNumberSpaces: HashSet<Int>,
+        ticket: Int,
+        row: Int
+    ) {
+        var columnIterationsLeft = 8
+        columnIndices.forEach { column ->
+            if (!mustBlankSpaces.contains(column) && !mustNumberSpaces.contains(column)) {
+                if (canBeBlank(ticket, row, column) && isBlank(ticket, row, column)) {
+                    addBlank(ticket, row, column)
+                } else {
+                    addNumber(ticket, row, column)
+                }
+            }
+            columnIterationsLeft--
+        }
+    }
+
+    private fun setInvalidIfNeeded(ticket: Int, row: Int) {
+        if (isRowInvalidValid(ticket, row)) {
+            sixTickets.invalid = true
+        }
+    }
+
+    private fun isRowInvalidValid(ticket: Int, row: Int) =
+        sixTickets.tickets[ticket].getRow(row).count { it > 0 } != NUMBERS_IN_ROW
+
+    private fun returnOrRegenerateIfInvalid(): SixTickets {
+        return if (sixTickets.invalid) {
+            generateTickets()
+        } else {
+            sixTickets
+        }
+    }
+
+    abstract fun mustBeBlank(
+        ticket: Int,
+        row: Int,
+        column: Int,
+        columnIterator: Int,
+        columnIndices: List<Int>
+    ): Boolean
+
+    protected abstract fun doInit()
+
+    protected abstract fun nextNumber(ticket: Int, row: Int, column: Int): Int
+
+    protected abstract fun mustBeNumber(ticket: Int, row: Int, column: Int, columnIterationsLeft: Int): Boolean
+
+    protected abstract fun canBeBlank(ticket: Int, row: Int, column: Int): Boolean
+
+    protected abstract fun isBlank(ticket: Int, row: Int, column: Int): Boolean
+
+    protected fun remainingTotalRows(ticket: Int, row: Int): Int {
+        return ((TICKETS - (ticket + 1)) * ROWS) + (ROWS - row)
+    }
+
+    protected fun getRemainingNumbersInRow(ticket: Int, row: Int): Int {
+        return remainingNumbersInRow[ticket * ROWS + row]!!
+    }
+
+    protected fun decrementRemainingNumbersInRow(ticket: Int, row: Int) {
+        remainingNumbersInRow[ticket * ROWS + row] = remainingNumbersInRow[ticket * ROWS + row]!! - 1
+    }
+
+    protected fun maxPossibleBlanksInColumn(ticket: Int, row: Int, column: Int): Int {
+        val remainingFullTickets = TICKETS - (ticket + 1)
+        var possibleBlanks = remainingFullTickets * 2
+        var possibleBlanksInTicketColumn = 0
+        for (i in row until ROWS) {
+            if (sixTickets.tickets[ticket].canBeBlankByColumn(i, column)) {
+                possibleBlanksInTicketColumn++
+            }
+        }
+        possibleBlanks += min(possibleBlanksInTicketColumn, 2)
+        return possibleBlanks
+    }
+
+    protected fun maxPossibleBlanksInRow(
+        ticket: Int,
+        row: Int,
+        columnIterator: Int,
+        columnIndices: List<Int>
+    ): Int {
+        var possibleBlanks = 0
+        for (i in columnIterator until columnIndices.size) {
+            if (canBeBlank(ticket, row, columnIndices[i])) {
+                possibleBlanks++
+            }
+        }
+        return possibleBlanks
+    }
+
+    private fun initNewStripOfSix() {
+        sixTickets = SixTickets()
+        remainingBlanksInColumn = hashMapOf(
+            Pair(0, 9),
+            Pair(1, 8),
+            Pair(2, 8),
+            Pair(3, 8),
+            Pair(4, 8),
+            Pair(5, 8),
+            Pair(6, 8),
+            Pair(7, 8),
+            Pair(8, 7),
+        )
+        remainingNumbersInRow = HashMap()
+        for (i in 0 until TOTAL_ROWS_IN_STRIP_OF_SIX) {
+            remainingNumbersInRow[i] = NUMBERS_IN_ROW
+        }
+        doInit()
+    }
+
+    private fun addNumber(ticket: Int, row: Int, column: Int) {
+        val number = nextNumber(ticket, row, column)
+        sixTickets.tickets[ticket].setValue(row, column, number)
+    }
+
+    private fun addBlank(ticket: Int, row: Int, column: Int) {
+        sixTickets.tickets[ticket].setValue(row, column, BLANK)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGenerator.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGenerator.kt
new file mode 100644
index 0000000..da6b81a
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGenerator.kt
@@ -0,0 +1,122 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+import com.attilapalfi.lindar.bingoticketgenerator.random.RandomProvider
+import java.util.stream.IntStream
+
+class ArrayBasedTicketGenerator(randomProvider: RandomProvider) : AbstractTicketGenerator(randomProvider) {
+    private lateinit var numberArrays: ArrayList<ArrayList<Int>>
+    private lateinit var isBlankArrays: ArrayList<ArrayList<ArrayList<Boolean>>>
+
+    override fun doInit() {
+        numberArrays = copyNumbersAsArrayList()
+        isBlankArrays = ArrayList(TICKETS)
+        IntStream.range(0, TICKETS).forEach {
+            isBlankArrays.add(copyBlanksAsArrayList())
+        }
+    }
+
+    override fun nextNumber(ticket: Int, row: Int, column: Int): Int {
+        if (numberArrays[column].isEmpty()) {
+            // this should not happen
+            sixTickets.invalid = true
+            return BLANK
+        }
+        decrementRemainingNumbersInRow(ticket, row)
+        val randomIndex = randomProvider.nextInt(numberArrays[column].size)
+        return numberArrays[column].removeAt(randomIndex)
+    }
+
+    override fun mustBeNumber(ticket: Int, row: Int, column: Int, columnIterationsLeft: Int): Boolean {
+        if (getRemainingNumbersInRow(ticket, row) == columnIterationsLeft + 1) {
+            return true
+        }
+        val remainingTotalRows = remainingTotalRows(ticket, row)
+        return remainingTotalRows == numberArrays[column].size
+    }
+
+    override fun mustBeBlank(
+        ticket: Int,
+        row: Int,
+        column: Int,
+        columnIterator: Int,
+        columnIndices: List<Int>
+    ): Boolean {
+        val mustBeBlankByRow =
+            remainingBlanksInRow(ticket, row) == maxPossibleBlanksInRow(ticket, row, columnIterator, columnIndices)
+        val mustBeBlankByColumn = remainingBlanksInColumn[column]!! == maxPossibleBlanksInColumn(ticket, row, column)
+
+        if (mustBeBlankByRow || mustBeBlankByColumn) {
+            remainingBlanksInColumn[column] = remainingBlanksInColumn[column]!! - 1
+            isBlankArrays[ticket][row].removeAt(0)
+            return true
+        }
+
+        return false
+    }
+
+    override fun canBeBlank(ticket: Int, row: Int, column: Int): Boolean {
+        val canBeBlankByColumn = sixTickets.tickets[ticket].canBeBlankByColumn(row, column)
+        val canBeBlankByRow = isBlankArrays[ticket][row][0]
+        return canBeBlankByColumn && canBeBlankByRow && remainingBlanksInColumn[column]!! > 0
+    }
+
+    override fun isBlank(ticket: Int, row: Int, column: Int): Boolean {
+        val randomIndex = randomProvider.nextInt(isBlankArrays[ticket][row].size)
+        val isBlank = isBlankArrays[ticket][row].removeAt(randomIndex)
+        if (isBlank) {
+            remainingBlanksInColumn[column] = remainingBlanksInColumn[column]!! - 1
+        }
+        return isBlank
+    }
+
+    private fun remainingBlanksInRow(ticket: Int, row: Int) = isBlankArrays[ticket][row].count { it }
+
+    private fun copyNumbersAsArrayList(): ArrayList<ArrayList<Int>> {
+        val numberArrays = ArrayList<ArrayList<Int>>(numberArrayStorage.size)
+        numberArrayStorage.forEach {
+            numberArrays.add(arrayListOf(*it.copyOf().toTypedArray()))
+        }
+        return numberArrays
+    }
+
+    private fun copyBlanksAsArrayList(): ArrayList<ArrayList<Boolean>> {
+        val isBlankArrays = ArrayList<ArrayList<Boolean>>(isBlankArrayStorage.size)
+        isBlankArrayStorage.forEach {
+            isBlankArrays.add(arrayListOf(*it.copyOf().toTypedArray()))
+        }
+        return isBlankArrays
+    }
+
+    companion object {
+        private val numberArrayStorage: Array<IntArray> = Array(COLUMNS) { arrayIndex ->
+            if (arrayIndex == 0) {
+                val array = IntArray(NUMBERS_IN_FIRST_COLUMN)
+                for (i in 1..array.size) {
+                    array[i - 1] = i
+                }
+                array
+            } else if (arrayIndex < 8) {
+                val array = IntArray(NUMBERS_IN_MIDDLE_COLUMNS)
+                for (i in array.indices) {
+                    array[i] = 10 * arrayIndex + i
+                }
+                array
+            } else {
+                val array = IntArray(NUMBERS_IN_LAST_COLUMN)
+                for (i in array.indices) {
+                    array[i] = 10 * arrayIndex + i
+                }
+                array
+            }
+        }
+
+        private val isBlankArrayStorage: Array<BooleanArray> = Array(3) {
+            val array = BooleanArray(COLUMNS)
+            for (i in array.indices) {
+                array[i] = i < BLANKS_IN_ROW
+            }
+            array
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/SixTickets.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/SixTickets.kt
new file mode 100644
index 0000000..708472f
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/SixTickets.kt
@@ -0,0 +1,20 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+import java.util.stream.IntStream
+
+class SixTickets {
+    val tickets: ArrayList<Ticket> = ArrayList(6)
+    var invalid: Boolean = false
+
+    init {
+        IntStream.range(0, TICKETS).forEach {
+            tickets.add(Ticket())
+        }
+    }
+
+    override fun toString(): String {
+        val stringBuilder = StringBuilder()
+        tickets.forEach { stringBuilder.append(it).append("\n") }
+        return stringBuilder.toString()
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/Ticket.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/Ticket.kt
new file mode 100644
index 0000000..9d930ee
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/Ticket.kt
@@ -0,0 +1,79 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+class Ticket {
+
+    private val ticket: IntArray = IntArray(SPACES_IN_TICKET)
+    private val ticketValueComparator = TicketValueComparator()
+
+    fun setValue(row: Int, column: Int, value: Int) {
+        if (row == 0) {
+            ticket[0 * COLUMNS + column] = value
+        } else if (row == 1) {
+            val array = intArrayOf(getValue(0, column), value)
+            val sorted = array.sortedWith(ticketValueComparator)
+            ticket[0 * COLUMNS + column] = sorted[0]
+            ticket[1 * COLUMNS + column] = sorted[1]
+        } else if (row == 2) {
+            val array = intArrayOf(getValue(0, column), getValue(1, column), value)
+            val sorted = array.sortedWith(ticketValueComparator)
+            ticket[0 * COLUMNS + column] = sorted[0]
+            ticket[1 * COLUMNS + column] = sorted[1]
+            ticket[2 * COLUMNS + column] = sorted[2]
+        }
+    }
+
+    fun getValue(row: Int, column: Int): Int {
+        return ticket[row * COLUMNS + column]
+    }
+
+    fun canBeBlankByColumn(row: Int, column: Int): Boolean {
+        val otherRow1 = (row + 1) % ROWS
+        val otherRow2 = (row + 2) % ROWS
+        return getValue(otherRow1, column) != BLANK || getValue(otherRow2, column) != BLANK
+    }
+
+    fun getValues(): List<Int> {
+        return arrayListOf(*ticket.toTypedArray())
+    }
+
+    fun getRow(row: Int): IntArray {
+        return ticket.copyOfRange(row * COLUMNS, (row + 1) * COLUMNS)
+    }
+
+    fun getRowsOfTicket(): List<List<Int>> {
+        val rows = ArrayList<ArrayList<Int>>()
+        for (i in 0 until SPACES_IN_TICKET) {
+            val rowIndex: Int = i / COLUMNS
+            if (i % COLUMNS == 0) {
+                rows.add(ArrayList())
+            }
+            rows[rowIndex].add(ticket[i])
+        }
+        return rows
+    }
+
+    fun getColumnsOfTicket(): List<List<Int>> {
+        val columns = ArrayList<ArrayList<Int>>()
+        for (i in 0 until COLUMNS) {
+            columns.add(ArrayList())
+        }
+        for (row in 0 until ROWS) {
+            for (column in 0 until COLUMNS) {
+                columns[column].add(getValue(row, column))
+            }
+        }
+        return columns
+    }
+
+    override fun toString(): String {
+        val stringBuilder = StringBuilder()
+        for (row in 0 until ROWS) {
+            for (column in 0 until COLUMNS) {
+                stringBuilder.append(getValue(row, column)).append(" ")
+            }
+            stringBuilder.append("\n")
+        }
+        stringBuilder.append("\n---------------------\n")
+        return stringBuilder.toString()
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketGenerator.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketGenerator.kt
new file mode 100644
index 0000000..d596a7d
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketGenerator.kt
@@ -0,0 +1,5 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+sealed interface TicketGenerator {
+    fun generateTickets(): SixTickets
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparator.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparator.kt
new file mode 100644
index 0000000..01e828e
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparator.kt
@@ -0,0 +1,12 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+class TicketValueComparator : Comparator<Int> {
+
+    override fun compare(o1: Int, o2: Int): Int {
+        return if (o1 == BLANK || o2 == BLANK || o1 == 0 || o2 == 0) {
+            0
+        } else {
+            o1.compareTo(o2)
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/BingoController.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/BingoController.kt
new file mode 100644
index 0000000..80580b6
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/BingoController.kt
@@ -0,0 +1,18 @@
+package com.attilapalfi.lindar.bingoticketgenerator.web
+
+import org.springframework.http.ResponseEntity
+import org.springframework.stereotype.Controller
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RequestMapping
+
+@Controller
+@RequestMapping("bingo")
+class BingoController(
+    private val ticketGenerator: TicketGeneratorService
+) {
+
+    @GetMapping("newStrips", produces = ["text/formatted"])
+    fun generateNewStrips(): ResponseEntity<String> {
+        return ResponseEntity.ok(ticketGenerator.generateStripOfSix().toString())
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/StripsResponse.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/StripsResponse.kt
new file mode 100644
index 0000000..c150d55
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/StripsResponse.kt
@@ -0,0 +1,24 @@
+package com.attilapalfi.lindar.bingoticketgenerator.web
+
+data class StripsResponse(val tickets: List<TicketResponse>) {
+    override fun toString(): String {
+        val stringBuilder = StringBuilder()
+        tickets.forEach {
+            stringBuilder.append(it.toString())
+                .append("\n-----------------------------------\n")
+        }
+        return stringBuilder.toString()
+    }
+}
+
+data class TicketResponse(
+    val rows: List<List<Int>>
+) {
+    override fun toString(): String {
+        val stringBuilder = StringBuilder()
+        rows.forEach { row ->
+            stringBuilder.append(row.toString()).append("\n")
+        }
+        return stringBuilder.toString()
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/TicketGeneratorService.kt b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/TicketGeneratorService.kt
new file mode 100644
index 0000000..a02a7b0
--- /dev/null
+++ b/src/main/kotlin/com/attilapalfi/lindar/bingoticketgenerator/web/TicketGeneratorService.kt
@@ -0,0 +1,19 @@
+package com.attilapalfi.lindar.bingoticketgenerator.web
+
+import com.attilapalfi.lindar.bingoticketgenerator.random.RandomProvider
+import com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator.ArrayBasedTicketGenerator
+import com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator.TicketGenerator
+import org.springframework.stereotype.Service
+
+@Service
+class TicketGeneratorService(private val simpleRandomProvider: RandomProvider) {
+
+    fun generateStripOfSix(): StripsResponse {
+        val ticketGenerator: TicketGenerator = ArrayBasedTicketGenerator(simpleRandomProvider)
+        val sixTickets = ticketGenerator.generateTickets()
+
+        return StripsResponse(
+            tickets = sixTickets.tickets.map { ticket -> TicketResponse(ticket.getRowsOfTicket()) }
+        )
+    }
+}
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
new file mode 100644
index 0000000..2df5b15
--- /dev/null
+++ b/src/main/resources/application.yml
@@ -0,0 +1,4 @@
+logging:
+  level:
+    root: INFO
+    org.springframework.web: DEBUG
diff --git a/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/performancetest/PerformanceTest.kt b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/performancetest/PerformanceTest.kt
new file mode 100644
index 0000000..1740659
--- /dev/null
+++ b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/performancetest/PerformanceTest.kt
@@ -0,0 +1,55 @@
+package com.attilapalfi.lindar.bingoticketgenerator.performancetest
+
+import com.attilapalfi.lindar.bingoticketgenerator.random.SimpleRandomProvider
+import com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator.ArrayBasedTicketGenerator
+import org.junit.jupiter.api.Test
+import java.util.concurrent.Executors
+import java.util.concurrent.Future
+
+class PerformanceTest {
+
+    private val randomProvider = SimpleRandomProvider()
+
+    @Test
+    fun `measure time for 10_000 strip generation`() {
+        warmUpJvm()
+
+        val strips = 10_000
+        val startTime = System.currentTimeMillis()
+        for (i in 0 until strips) {
+            ArrayBasedTicketGenerator(randomProvider).generateTickets()
+        }
+        val executionTime = System.currentTimeMillis() - startTime
+        println("Generated $strips strips in $executionTime ms.")
+    }
+
+    @Test
+    fun `measure time for 100_000 strip generation in parallel`() {
+        warmUpJvm()
+
+        val strips = 100_000
+        val startTime = System.currentTimeMillis()
+        val threads = Runtime.getRuntime().availableProcessors()
+        val executorService = Executors.newFixedThreadPool(threads)
+        val chunkSize = strips / threads
+        val futures = mutableListOf<Future<*>>()
+        for (i in 0 until threads) {
+            val future = executorService.submit {
+                for (j in 0..chunkSize) {
+                    ArrayBasedTicketGenerator(randomProvider).generateTickets()
+                }
+            }
+            futures.add(future)
+        }
+        futures.forEach { it.get() }
+        executorService.shutdown()
+        val executionTime = System.currentTimeMillis() - startTime
+        println("Generated $strips strips in parallel in $executionTime ms.")
+    }
+
+    private fun warmUpJvm() {
+        for (i in 0 until 1000) {
+            ArrayBasedTicketGenerator(randomProvider).generateTickets()
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGeneratorTest.kt b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGeneratorTest.kt
new file mode 100644
index 0000000..a0391dd
--- /dev/null
+++ b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/ArrayBasedTicketGeneratorTest.kt
@@ -0,0 +1,122 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+import com.attilapalfi.lindar.bingoticketgenerator.random.DeterministicRandomProvider
+import com.attilapalfi.lindar.bingoticketgenerator.random.SimpleRandomProvider
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.fail
+
+class ArrayBasedTicketGeneratorTest {
+
+    private lateinit var underTest: ArrayBasedTicketGenerator
+
+    @Test
+    fun runAllTestsMultipleTimes() {
+        for (i in 0 .. 1000) {
+            `test with deterministic random provider`()
+            `test with simple random provider`()
+        }
+    }
+
+    @Test
+    fun `test with deterministic random provider`() {
+        underTest = ArrayBasedTicketGenerator(DeterministicRandomProvider())
+
+        val sixTickets = underTest.generateTickets()
+        println(sixTickets)
+
+        validateSixTickets(sixTickets)
+    }
+
+    @Test
+    fun `test with simple random provider`() {
+        underTest = ArrayBasedTicketGenerator(SimpleRandomProvider())
+
+        val sixTickets = underTest.generateTickets()
+        println(sixTickets)
+
+        validateSixTickets(sixTickets)
+    }
+
+    private fun validateSixTickets(sixTickets: SixTickets) {
+        val numberSet = HashSet<Int>(90)
+        for (i in 1..90) {
+            numberSet.add(i)
+        }
+        var iterator = 0
+        sixTickets.tickets.forEachIndexed { ticketIndex, ticket ->
+            validateRowRules(ticketIndex, ticket)
+            validateColumnRules(ticketIndex, ticket)
+            ticket.getValues().forEach { value ->
+                val ticketValueIndex = iterator - (ticketIndex * 27)
+                val rowInTicket = ticketValueIndex / 9
+                val columnInTicket = ticketValueIndex - (rowInTicket * 9)
+
+                if (value != BLANK) {
+                    validateValueIsNotDuplicated(value, numberSet)
+                    validateValueIsInCorrectColumn(value, columnInTicket)
+                }
+                iterator++
+            }
+        }
+    }
+
+    private fun validateRowRules(ticketIndex: Int, ticket: Ticket) {
+        val rows = ticket.getRowsOfTicket()
+        assertEquals(3, rows.size)
+        rows.forEachIndexed { rowIndex, row ->
+            val numbersInRow = row.count { it > 0 }
+            val blanksInRow = row.count { it < 0 }
+            assertEquals(
+                5,
+                numbersInRow,
+                "Row '$rowIndex' in ticket '$ticketIndex' has invalid amount of numbers: '$numbersInRow'"
+            )
+            assertEquals(
+                4,
+                blanksInRow,
+                "Row '$rowIndex' in ticket '$ticketIndex' has invalid amount of blanks: '$blanksInRow'"
+            )
+        }
+    }
+
+    private fun validateColumnRules(ticketIndex: Int, ticket: Ticket) {
+        val columns = ticket.getColumnsOfTicket()
+        assertEquals(9, columns.size)
+        columns.forEachIndexed { columnIndex, column ->
+            val blanksInColumn = column.count { it < 0 }
+            assertTrue(
+                blanksInColumn < 3,
+                "Invalid number of blanks in column '$columnIndex' of ticket '$ticketIndex': '$blanksInColumn'"
+            )
+
+            val sortedColumn = column.toTypedArray()
+            sortedColumn.sortWith(TicketValueComparator())
+
+            assertArrayEquals(
+                sortedColumn,
+                column.toTypedArray(),
+                "Values in column '$columnIndex' in ticket '$ticketIndex' are not in ascending order"
+            )
+        }
+    }
+
+    private fun validateValueIsNotDuplicated(value: Int, numberSet: HashSet<Int>) {
+        if (!numberSet.contains(value)) {
+            fail("Number '$value' was duplicated in the tickets.")
+        } else {
+            numberSet.remove(value)
+        }
+    }
+
+    private fun validateValueIsInCorrectColumn(value: Int, columnInTicket: Int) {
+        if (value == 90) {
+            assertEquals(8, columnInTicket)
+        } else {
+            if (value < columnInTicket * 10 || value >= columnInTicket * 10 + 10) {
+                fail("Invalid value in column '$columnInTicket': '$value'")
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparatorTest.kt b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparatorTest.kt
new file mode 100644
index 0000000..a5e3561
--- /dev/null
+++ b/src/test/kotlin/com/attilapalfi/lindar/bingoticketgenerator/ticketgenerator/TicketValueComparatorTest.kt
@@ -0,0 +1,21 @@
+package com.attilapalfi.lindar.bingoticketgenerator.ticketgenerator
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+
+class TicketValueComparatorTest {
+
+    private val ticketValueComparator = TicketValueComparator()
+
+    @Test
+    fun testComparator() {
+        val input = intArrayOf(33, 31, -1)
+        val expected = intArrayOf(31, 33, -1)
+
+        val result = input.sortedWith(ticketValueComparator)
+
+        println(input.toList())
+        assertArrayEquals(expected, result.toIntArray())
+    }
+
+}
\ No newline at end of file