LeetCode Beginner to Expert Road Path 1

If you don’t know where to start, why not try the following algorithm categories?

Hash

• Question 1 : Two Sum
• Question 387 : First Unique Character in a String

Linked List Operations

• Question 2 : Add Two Numbers
• Question 19 : Remove Nth Node From End of List
• Question 25 : Reverse Nodes in k-Group
• Question 61 : Rotate List
• Question 138 : Copy List with Random Pointer
• Question 206 : Reverse Linked List

Two Pointers Traversal / Sliding Window

• Question 3 : Longest Substring Without Repeating Characters
• Question 11 : Container With Most Water
• Question 15 : 3Sum
• Question 16 : 3Sum Closest
• Question 26 : Remove Duplicates from Sorted Array
• Question 42 : Trapping Rain Water
• Question 121 : Best Time to Buy and Sell Stock
• Question 209 : Minimum Size Subarray Sum

Fast and Slow Pointers Traversal

• Question 141 : Linked List Cycle
• Question 202 : Happy Number
• Question 876 : Middle of the Linked List

Interval Merge

• Question 56 : Merge Intervals

String Manipulation

• Question 6 : ZigZag Conversion
• Question 14 : Longest Common Prefix
• Question 763 : Partition Labels

Digital Operations

• Question 7 : Reverse Integer
• Question 8 : String to Integer (atoi)
• Question 9 : Palindrome Number
• Question 43 : Multiply Strings
• Question 172 : Factorial Trailing Zeroes
• Question 258 : Add Digits

Array Operations

• Question 54 : Spiral Matrix
• Question 73 : Set Matrix Zeroes
• Question 78 : Subsets
• Question 384 : Shuffle an Array
• Question 581 : Shortest Unsorted Continuous Subarray
• Question 945 : Minimum Increment to Make Array Unique

Stack

• Question 20 : Valid Parentheses
• Question 32 : Longest Valid Parentheses
• Question 155 : Min Stack
• Question 224 : Basic Calculator
• Question 232 : Implement Queue using Stacks
• Question 316 : Remove Duplicate Letters

Heap

• Question 215 : Kth Largest Element in an Array
• Question 347 : Top K Frequent Elements

Recursion

• Question 21 : Merge Two Sorted Lists
• Question 101 : Symmetric Tree
• Question 104 : Maximum Depth of Binary Tree
• Question 226 : Invert Binary Tree
• Question 236 : Lowest Common Ancestor of a Binary Tree
• Question 1325 : Delete Leaves With a Given Value

Divide and Conquer / Dichotomy

• Question 23 : Merge k Sorted Lists
• Question 33 : Search in Rotated Sorted Array
• Question 34 : Find First and Last Position of Element in Sorted Array

Dynamic Programming

• Question 5 : Longest Palindromic Substring
• Question 53 : Maximum Subarray
• Question 62 : Unique Paths
• Question 64 : Minimum Path Sum
• Question 70 : Climbing Stairs
• Question 118 : Pascal’s Triangle
• Question 300 : Longest Increasing Subsequence
• Question 1143 : Longest Common Subsequence
• Question 1277 : Count Square Submatrices with All One

Backtracking

• Question 10 : Regular Expression Matching
• Question 22 : Generate Parentheses
• Question 40 : Combination Sum II
• Question 46 : Permutations

Trie

• Question 648 : Replace Words

Tree Traversal

• Question 94 : Binary Tree Inorder Traversal
• Question 102 : Binary Tree Level Order Traversal
• Question 110 : Balanced Binary Tree
• Question 144 : Binary Tree Preorder Traversal
• Question 145 : Binary Tree Postorder Traversal

Binary Search Tree

• Question 98 : Validate Binary Search Tree
• Question 450 : Delete Node in a BST
• Question 701 : Insert into a Binary Search Tree