Add Lua version

Author: firejox

.travis.yml

@@ -3,6 +3,9 @@ language: crystal
 before_install:
   - sudo apt-get -qq update
   - sudo apt-get install -y ruby default-jdk haskell-platform python3
+  - wget http://www.lua.org/ftp/lua-5.3.4.tar.gz
+  - tar -zxv -f lua-5.3.4.tar.gz
+  - pushd lua-5.3.4 && make CFLAGS="-O2 -fPIC -DLUA_COMPAT_5_2 -DLUA_COMPAT_5_1" linux && sudo make INSTALL_TOP=/usr install && popd
 
 install: make clean build
 

Makefile

@@ -15,6 +15,7 @@ build:
 	g++ -O2 main.cpp -o $(BIN_DIR)/cpp
 	javac -d $(BIN_DIR) Main.java
 	ghc -O2 main.hs -outputdir=$(BUILD_DIR) -o $(BIN_DIR)/haskell
+	luac -o $(BIN_DIR)/lua main.lua
 
 test:
 	mkdir $(TMP_DIR)
@@ -32,4 +33,6 @@ test:
 	@cmp $(TMP_DIR)/crystal.out $(TMP_DIR)/haskell.out || (echo "Failed: Haskell" && exit 1)
 	python3 main.py < $(TMP_DIR)/test_data.in > $(TMP_DIR)/python3.out
 	@cmp $(TMP_DIR)/crystal.out $(TMP_DIR)/python3.out || (echo "Failed: Python3" && exit 1)
+	lua $(BIN_DIR)/lua < $(TMP_DIR)/test_data.in > $(TMP_DIR)/lua.out
+	@cmp $(TMP_DIR)/crystal.out $(TMP_DIR)/lua.out || (echo "Failed: Lua" && exit 1)
 	@echo "Passed"

README.md

@@ -13,6 +13,7 @@ Solve 2D Rank Finding Problem in Several Languages
 - Java
 - Haskell
 - Python 3
+- Lua
 
 ## Problem
 
@@ -80,3 +81,4 @@ Your output should consist of a single line for each test case containing n numb
 - [scps940707](https://github.com/scps940707) YyWang - Java
 - [sifmelcara](https://github.com/sifmelcara) mingchuan - Haskell
 - [chuanchan1116](https://github.com/chuanchan1116) William Tsai - Python 3
+- [firejox](https://github.com/firejox) Firejox - Lua

main.lua

@@ -0,0 +1,72 @@
+local Point = {}
+Point.__index = Point
+Point.__lt = function(a, b)
+  if a.x == b.x then
+    return a.y < b.y
+  end
+  return a.x < b.x
+end
+
+function Point:new(x, y, idx)
+  return setmetatable({ x = x, y = y, idx = idx }, Point)
+end
+
+while true do
+  local ranks = {}
+
+  function find_ranks(pts)
+    local sz = #pts
+    local l_sz = math.floor(sz / 2)
+    local r_sz = sz - l_sz
+
+    if sz == 1 then
+      return pts
+    end
+
+    local pts_l = find_ranks(table.pack(table.unpack(pts, 1, l_sz)))
+    local pts_r = find_ranks(table.pack(table.unpack(pts, l_sz + 1)))
+    local res = {}
+    local i, j = 1, 1
+
+    while true do
+      if pts_l[i].y <= pts_r[j].y then
+        table.insert(res, pts_l[i])
+        i = i + 1
+        if i > l_sz then
+          while j <= r_sz do
+            ranks[pts_r[j].idx] = ranks[pts_r[j].idx] + i - 1
+            table.insert(res, pts_r[j])
+            j = j + 1
+          end
+          break
+        end
+      else
+        table.insert(res, pts_r[j])
+        ranks[pts_r[j].idx] = ranks[pts_r[j].idx] + i - 1
+        j = j + 1
+        if j > r_sz then
+          table.move(pts_l, i, l_sz, #res + 1, res)
+          break
+        end
+      end
+    end
+
+    return res
+  end
+
+  local pts = {}
+  local n = io.read("*n")
+  if n == 0 then
+    break
+  end
+
+  for i = 1, n do
+    x, y = io.read("*n", "*n")
+    pts[i] = Point:new(x, y, i)
+    ranks[i] = 0
+  end
+
+  table.sort(pts, cmp)
+  find_ranks(pts)
+  print(table.concat(ranks, ' '))
+end