Algorithms and Data Structures in Apex

Welcome this repo is meant as a companion to my youtube series.

Recursion

• intro to recursion
  • Watch it on Youtube
  • I provided some code challenges for writing recursive code. The answers are in the repo. But try to solve these first.
    1. Get the sum or a range of numbers.
    2. Compute a number to a certain power.
    3. Determine if a word is a palindrome
    4. Compute a number in the fibonacci sequence
    5. Reverse a string

Search

• Linear Search
• Watch it on Youtube
  • just fine for a small data set. Runs at o(N)
• Binary Search
  • The algo that made me feel like a genius the first time I saw it and understood it. It needs a sorted list to work but runs at o(Log N).

Sorting

• Bubble Sort
  • Watch it on Youtube
  • Pretty much only used as an example of what not do it. But perfect for undertanding why nested for loops are bad.
• Selection Sort
  • Like Bubble Sort but puts the smallest value into sorted position instead of the largest. Algo runs at O(n^2) but is slightly optomized compared to Bubble Sort. It does one swap per pass for the lowest value.
• Insertion Sort
  • Runs at O(n^2). Iterates from index 1 to final position in the collection. If value is smaller than its predecessor it compares to elements before and swaps.
• Merg Sort -The first of our "advanced sorting algos" and an important one to understand. It is a divide and conquer algo and runs at O(nLogn). It has a space complexity of O(n).

Data Structures

• Singly Linked List 🚧
  • A data structure with a head, tail and length property. Unlike a Apex List it has no index. Each node in the list contains a pointer to the next element. You can not use collection[i] instead it is collection.next().
  • It contains the properties head, length and tail.