This is an overview of 75+ LeetCode questions that will prepare you for coding interviews - including explanations of common patterns/ways to use to solve these problems.

The key is for you to change my explanations to yours - in a way that allows you to remember how you solved it.

💡 Code on Github: https://github.com/tobiadey/LeetCode-Questions

Youtube Channels: LeetCode & Back To Back SWE

Common Coding Interview Patterns

Common Coding Interview Patterns:

• HashMap:
  • A data structure that stores key-value pairs.
• Recursion: Time O(n),Space O(n)
  • A function that calls itself.
• **Depth First Search(DFS): Time O(|v|+|e|),Space O(|v|)**
  • A searching algorithm that favours depth over breadth. Implemented using a stack user-defined stack or the call stack from using recursion.
  • Uses cases include backtracking, and exhausting possible paths.
• **Breath First Search(BFS): Time O(|v|+|e|),Space O(|v|)**
  • A searching algorithm that favours breadth over depth. Uses a queue. Implemented iteratively.
  • Uses cases include: checking if a path exists between 2 nodes
• Binary Search: Time O(logn),Space O(1)
  • Searching algorithm for sorted data structures.
• Sliding Window
  • A problem-solving technique that involves using pointers and moving them across an array in order to solve the problem
• Heaps:
  • A tree-based Data structure that is a complete binary tree. e.g include Max & Min heap.

Array - [1,2,3,4,5]

• Two Sum - Stores each value in a hashMap. Before hashing check, if the difference has already been hashed.
• Best Time to Buy and Sell Stock - Find local min and search for local max, sliding window;
• Contains Duplicate - Use sets operation then compare lengths
• Product of Array Except Self - make two passes, first in order, second in reverse, to compute products. (you will need the prefix & suffix to compute these values)
• Maximum Subarray - Pattern: prev subarray can't be negative, dynamic programming: compute max sum for each prefix