I have linked the solutions to the problems I've solved.

Problems

Array

Array

• Remove duplicates from sorted array

• Search insert position

• Fibonacci series

• Spiral matrix

• Find the smallest and second smallest element in an array

• First missing positive

• Sort 0s 1s 2s

• Kadane algorithm

• Majority element ( > n/2 times )

• Majority element ( > n/3 times )

• Two sum

• Two sum ii

• Three sum

• Rain water tapping

• Product of array except self

• Search min in rotated sorted array

• Search in rotated sorted array

• Search in rotated sorted array - ii

• Contains Duplicate

• Container with most water

• Maximum product subarray

• Merge two overlapping intervals

• Valid parenthesis

• Missing Number

• Valid Sudoku

• Valid Palindrome

• Set Matrix Zeros

• Longest Consecutive Sequence

• Next Permutation

• Count Palindromic substrings

• Convert Roman to Integer

• Convert Integer to Roman

TODO:

• Transpose of matrix
• Rotate Image
• Maximum Value in increasing - decreasing array
• Matrix Rotation in place
• Celebrity Problem
• Quicksort implementation - Kth smallest
• Median of two sorted array
• Maximum of all subarrays of size K

Sliding Window: Fixed

Sliding Window: Variable

• Minimum Window Substring

• Longest substring without repeating characters

• Longest Repeating Character Replacement

• Group Anagrams

• Longest subarray with sum k

• Count of subarrays with sum k

• Maximum sum of distinct subarrays with size k

• First Negative Integer in every window of size k

Stack & Queue

• NGR - Next Greatest Right
• NSL - Next Smallest Left
• Stock Span
• Max area Histogram
• Daily Temperatures

Heap

• kth Largest element
• Return K largest elements
• K Most frequenct elements
• Closest Points to origin
• Frequency Sort

Greedy

• Jump Game

• Gas Station

• N Meetings in one room

• Maximum Meetings in One Room (N meeting extended)

• Maximum Platforms

• Job Sequencing

• Fractional Knapsack

• Huffman Encoding

• Min cost of ropes

• Chocolate distribution problem

Bitwise

• Count number of ones
• Counting Bits
• Reverse Bits

Linked List

• Reverse a List

• Check if the List has a cycle

• Find the length of the Cycle

• Get the starting-node of the cycle

• Find the intersection node of two Lists

• Middle of a List

• Check Palindrome

• Get Nth node from end of LinkedList

• Remove Nth node from end of LinkedList

• Merge Two sorted LinkedList

• Merge K sorted LinkedList

• Add two linked lists

• Add two number

• Flattening a linked list

• Reverse a linked list in k-groups

• Rotate a LinkedList

Recursion & Backtracking

• Subsets-I
• Subsets-II
• Permutation-I
• Permutation-II
• Combination-sum-I
• Combination-sum-II
• N Queens - I
• Word Search
• Generate Correct Parenthesis

TODO:

• Combination-sum-iii
• Kth Permutation Sequence
• N Queens - II
• Rat Maze Problem
• Knight Walk Problem
• Pow(x, n)
• Sudoku Solver
• M Coloring Problem

Tree

Leetcode Tree Constructor

• InOrder Traversal- Recursive & Iterative
• Preorder Traversal - Recursive & Iterative
• Postorder Traversal - Recursive & Iterative
• kth smallest in BST
• Sum root to leaf
• Boundary nodes
• Depth of a BT
• Sum of all nodes
• Level order traversal;
• ZigZag order traversal
• Odd even level difference
• Count the number of leaf nodes
• Diameter of a Btree
• Is the BTree Balanced
• Left View
• Right View
• Vertical Order Traversal
• Top View
• Bottom View
• Path to Node
• Max Path sum
• Construct a binary tree from preorder
• Construct a binary tree from inorder and preorder
• Same Tree
• Is the BTree Symmetric
• Least common ancestor - Binary Tree
• Least common ancestor - Binary Search Tree
• Maximum width of a Binary Tree
• Serialize and Deserialize a Btree
• Is sub-tree
• Good Nodes
• Invert a BTree
• Merge two BTree
• Sorted Array to Balanced BTree
• Triangle min path sum
• Valid BTree
• House Robber III
• Bottom Left Tree Value
• Trim BST
• Has Path Sum
• BST Iterator
• Populating Next Right Pointers

TODO:

• [Siblings & Cousins]
• [Burn a tree]

Trie

• Build a Trie
• Design Add & Search Words

Dynamic Programming

Patterns

• 0/1 Knapsack
• Unbounded Knapsack
• Min Max Subsequences
• Partition DP

Mix DP

• Climbing Stairs
• House Robber
• House Robber II
• Min cost climbing stairs
• Decode Ways
• Pascal's Triangle
• Unique Paths
• Word Break
• Buy and Sell Stock I
• Buy and Sell Stock II
• Buy and Sell Stock III
• Buy and Sell Stock IV
• Best time to buy/sell stock with cooldown
• Jump Game - II
• Jump Game - III
• Unique BST
• Perfect Squares
• Regular Expression Matching
• All Possible Full Binary Tree
• Stone Game I
• Integer Break

I. 2-DP::

• Interleaving String
• Longest Increasing Path in matrix
• Distinct Subsequence
• Unique Paths II
• Minimum Path Sum
• Maximal Squared
• Paint Houses - I

II. 0/1 Knapsack

• Knapsack problem
• Subset sum problem
• Count of subset problem - Perfect Sum
• Equal Partition problem
• Minimum subset sum difference
• No. of subset with given difference
• Target sum

III. Unbounded Knapsack

• Rod cutting problem
• Coin Change 1 - min coins
• Coin Change 2 - max ways
• Combination IV

IV. Subsequence - Substring

• Length - Longest Common Subsequence

• Print - Longest Common Subsequence

• Length - Longest common substring

• Length - Shortest Common Supersequence

• Print - Shortest Common Supersequence

• Minimum number insertion or deletion

• Minimum number of deletions to make a palindrome

• Edit Distance

• Longest Palindromic subsequence

• Longest repeating subsequence

• Longest increasing subsequence

• Maximum Alternating Subsequence Sum

V Partition DP

• Matrix Chain Multiplication
• Palindrome Partitioning
• Print longest Palindromic substring

Graphs

Graph I

No	Questions	Way
1.	BFS - Implementation	Queue + visited[]
2.	DFS - Implementation	Visited[]
3.	Number of Provinces	BFS - disconnected components
4.	Number of Islands	Modified Number of Provinces + 1-degree traversal up, right, down, left
5.	Flood Fill	Modified Traversal
6.	Rotten Oranges	Modified BFS - With a Time Counter
7.	Detect cycle using BFS - Undirected Graph	Neighbour is visted => Neighbour is current node's parent
8.	Detect cycle using DFS - Undirected Graph	Neighbour is visted => Neighbour is current node's parent
9.	Detect cycle using DFS - Directed Graph	visited[] + dfsVisited[] (backtracking) : tracks visited path
10.	Topological Sort - DFS	visited[] + stk.push(node) backtracking
11.	Topological Sort - BFS - Kahn's Algorithm	indegree[] , Kahn Algorithm
12.	Detect cycle using DFS - Directed Graph	indegree[] or Kahn Algorithm
13.	Bipartite Graph - BFS	color[], color[currNode] == color[neighbour]
14.	Bipartite Graph - DFS	color[], color[currNode] == color[neighbour]
15.	Clone Graph	DFS + Mapping GivenNode to ClonedNode

Graph II

Note: Shortest Path Question will require a distance[] for every problem

No	Questions	Way
1.	Shortest Path - Non-Weighted + Undirected Graph	BFS + parent[]
2.	Shortest Path - Weighted + Directed Graph	Topological Stack + parent[]
3.	Shortest Path - Weighted Graph( UDG)	Djikstra Algorithm
4.	Shortest Path - In Binary Maze	Djikstra Algorithm

TODO:

• Templates

1. Construct Graph from given edges

• Problems
• Cheapest Flight in K stops
• Getting minimum distance to reach stop
• Minimum Spanning Tree - Prims Algorithm
• Kruskal Algorithm
• No of operations to make Network connected
• Bridges in Graph
• Atriculation Points in Graph
• KosaRaju's Algorithm
• Bellman Ford

Design

• LRU Cache
• Min Stack
• Kth Largest in the Stream