LeetCode Topics and Interview Questions Collection

Subject Category

Hash

• Question 1 : Sum of two numbers
• Question 387 : The first unique character in the string

Linked List Operations

• Question 2 : Add two numbers
• Question 19 : Delete the Nth node from the bottom of the linked list
• Question 25 : K set of flipped linked lists
• Question 61 : Rotating linked list
• Question 138 : Copy linked list with random pointer
• Question 206 : Reverse linked list

Double Pointer Traversal / Sliding Window

• Question 3 : Longest substring without repeated characters
• Question 11 : Container with the most water
• Question 15 : Sum of three numbers
• Question 16 : Closest sum of three numbers
• Question 26 : Delete duplicates in the sorted array
• Question 42 : Trapping-rain-water
• Question 121 : The best time to buy and sell stocks
• Question 209 : The smallest length sub-array

Fast and Slow Pointer Traversal

• Question 141 : Circular linked list
• Question 202 : Happy number
• Question 876 : Intermediate node of linked list

Interval Merge

• Question 56 : Merge interval

String Manipulation

• Question 6 : Zigzag transformation
• Question 14 : Longest common prefix
• Question 763 : Dividing letter interval

Digital Operations

• Question 7 : Integer inversion
• Question 8 : String conversion integer
• Question 9 : Palindrome Number
• Question 43 : String multiplication
• Question 172 : Zero after factorial
• Question 258 : Add everybody

Array Operations

• Question 54 : Spiral matrix
• Question 73 : Zero Matrix
• Question 78 : Subset
• Question 384 : Scrambling array
• Question 581 : Shortest unordered continuous subarray
• Question 945 : Minimum increment to make the array unique

Stack

• Question 20 : Valid brackets
• Question 32 : Longest valid bracket
• Question 155 : Minimal stack
• Question 224 : Basic calculator
• Question 232 : Implement queue with stack
• Question 316 : Remove duplicate letters

Heap

• Question 215 : The Kth largest element in the array
• Question 347 : Top K high frequency elements

Recursion

• Question 21 : Merge two ordered linked lists
• Question 101 : Symmetric binary tree
• Question 104 : Maximum Depth of Binary Tree
• Question 226 : Flip binary tree
• Question 236 : The nearest common ancestor of the binary tree

Divide and Conquer / Dichotomy

• Question 23 : Merge K sorted lists
• Question 33 : Search rotating sorted array
• Question 34 : Find the first and last position of an element in the sorted array

Dynamic Programming

• Question 5 : Longest palindrome substring
• Question 53 : Maximum Subsequence Sum
• Question 62 : Different path
• Question 64 : Minimum path sum
• Question 70 : Stair climbing
• Question 118 : Pascal's Triangle
• Question 300 : Longest Ascending Subsequence
• Question 1143 : Longest common subsequence
• Question 1277 : Square submatrix with all 1s

Backtracking

• Question 10 : Regular expression matching
• Question 22 : Bracket generation
• Question 40 : Combined sum 2
• Question 46 : All permutation

Tree Traversal

• Question 94 : In-order traversal of binary tree
• Question 102 : Binary tree traversal
• Question 110 : Balanced binary tree
• Question 144 : Preorder traversal of binary tree
• Question 145 : Post-order traversal of binary tree

Binary Search Trees

• Question 98 : Verify Binary Search Tree
• Question 450 : Delete nodes in binary search tree
• Question 701 : Insert operation in binary search tree

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Interview questions finishing

• Interview Questions Finishing