WhatsAlgo

Prepping for your coding interview? Want to learn data structures & algorithms but don't know where to start?

Well you have come to the right place. Data structures & algorithms are of key importance for anyone dealing with programming. Be a software engineer, a computer science student, or a fun enthusiast, having a firm grasp on various topics is crucial. This repository aims to provide implementations of many different data structures & algorithms from basic to some advanced topics. Learn and have a firm grasp on data structures & algorithms to ace your coding interviews and land that dream job!

Sorting Algorithms

• Selection Sort - O(n²)
• Bubble Sort - O(n²)
• Insertion Sort - O(n²)
• Merge Sort - O(n log n)
• Quick Sort - O(n²)
• Counting Sort - O(n + k)

Search Algorithms

• Linear Search - O(n)
• Binary Search - O(log n)
• Find Peak 1D - O(log n)
• Find Peak 2D - O(n)

Complete Search

• Generating Subsets - O(n • 2ⁿ)
• Generating Permutations (Backtracking) - O(n * n!)
• Generating Permutations (Lexicographic) - O(n * n!)

Data Structures

• Least Recently Used Cache
• Least Frequently Used Cache
• Running Median
• Trie
• Fenwick Tree
• Union-Find
• Prefix Sum - O(n)
• Prefix Sum 2D - O(n • m)
• Knuth–Morris–Pratt Algorithm - O(m + n)

Tree Algorithms

• Kruskal's Minimum Spanning Tree - O(E • log E)
• Prim's Minimum Spanning Tree - O(E • log E)

Dynamic Programming

• Maximum Subarray - O(n)
• Coin Change - O(n • c)
• Edit Distance - O(m • n)
• Longest Common Subsequence - O(m • n)
• Longest Increasing Subsequence - O(n • log n)
• nCr mod m - O(n • r)

Greedy Algorithms

• Coin Change - O(c)

Bit Manipulation

• Lowest Set Bit - O(1)
• Highest Set Bit - O(1)
• Count Set Bits - O(1)
• Reverse Bits - O(1)

Mathematics

• Primality Test - O(√n)
• Prime Factorization - O(√n)
• Fast Exponentiation - O(log n)
• Fast Modular Exponentiation - O(log n)
• Greatest Common Divisor - O(log(a + b))
• Least Common Multiple - O(log(a + b))
• nCr mod p - O(n)
• Extended Euclidean Algorithm - O(log(a + b))
• Modular Multiplicative Inverse - O(log m)

Miscellaneous

• Boyer–Moore Majority Vote - O(n • k)