130 Most Popular Leetcode Problems to crack coding interviews

I am currently working as SDE-II at Amazon. Here are some problems that are popular and will help in clearing coding interviews.

LeetCode covers a wide range of topics related to Data Structures, Algorithms, and various programming concepts. Here are the main topics that I have covered :

1. Array
2. String
3. Linked List
4. Stack
5. Queue
6. Binary Tree
7. Binary Search Tree (BST)
8. Graph
9. Hashing
10. Dynamic Programming
11. Greedy Algorithms
12. Backtracking
13. Divide and Conquer
14. Two Pointers
15. Sliding Window
16. Bit Manipulation
17. Sorting and Searching
18. Math
19. Recursion
20. Design and Implementation
21. Union Find (Disjoint Set)
22. Trie
23. Heap (Priority Queue)
24. Topological Sort
25. Breadth-First Search (BFS)
26. Depth-First Search (DFS)
27. Segment Tree
28. Fenwick Tree (Binary Indexed Tree)
29. Linked List Manipulation
30. Tree Traversals
31. Geometry

Array:

1. Two Sum
2. Container With Most Water
3. Best Time to Buy and Sell Stock
4. Product of Array Except Self

String:

1. Longest Substring Without Repeating Characters
2. Valid Parentheses
3. Valid Palindrome
4. Reverse Words in a String
5. Longest Palindromic Substring

Linked List:

1. Reverse Linked List
2. Merge Two Sorted Lists
3. Remove Nth Node From End of List
4. Linked List Cycle
5. Intersection of Two Linked Lists

Stack:

1. Min Stack
2. Evaluate Reverse Polish Notation
3. Daily Temperatures
4. Remove All Adjacent Duplicates in String

Queue:

1. Design Circular Queue
2. Implement Stack using Queues
3. Moving Average from Data Stream
4. Queue Reconstruction by Height
5. Number of Recent Calls

Binary Tree:

1. Maximum Depth of Binary Tree
2. Validate Binary Search Tree
3. Binary Tree Level Order Traversal
4. Lowest Common Ancestor of a Binary Tree
5. Symmetric Tree

Binary Search Tree (BST):

1. Kth Smallest Element in a BST
2. Convert Sorted Array to Binary Search Tree
3. Validate Binary Search Tree
4. Inorder Successor in BST
5. Range Sum of BST

Graph:

1. Number of Islands
2. Course Schedule
3. Word Search
4. Clone Graph
5. Pacific Atlantic Water Flow

Hashing:

1. Group Anagrams
2. Valid Sudoku
3. Subarray Sum Equals K
4. Longest Consecutive Sequence

Dynamic Programming:

1. Climbing Stairs
2. Longest Increasing Subsequence
3. Maximum Subarray
4. Coin Change
5. Unique Paths

Greedy Algorithms:

1. Jump Game
2. Task Scheduler
3. Minimum Number of Arrows to Burst Balloons
4. Non-overlapping Intervals
5. Gas Station

Backtracking:

1. N-Queens
2. Letter Combinations of a Phone Number
3. Permutations
4. Subsets
5. Palindrome Partitioning

Divide and Conquer:

1. Merge Sort
2. Quick Sort
3. Kth Largest Element in an Array
4. Maximum Subarray
5. Count of Smaller Numbers After Self

Two Pointers:

1. Two Sum II — Input array is sorted
2. Trapping Rain Water

Sliding Window:

1. Minimum Window Substring
2. Maximum Points You Can Obtain from Cards
3. Fruit Into Baskets
4. Longest Repeating Character Replacement

Bit Manipulation:

1. Single Number
2. Number of 1 Bits
3. Missing Number
4. Reverse Bits
5. Power of Two

Sorting and Searching:

1. Merge Intervals
2. First Missing Positive
3. Search in Rotated Sorted Array
4. Find First and Last Position of Element in Sorted Array

Math:

1. Palindrome Number
2. Roman to Integer
3. Integer to English Words
4. Pow(x, n)
5. Happy Number

Recursion:

1. Generate Parentheses
2. Combinations

Design and Implementation:

1. LRU Cache
2. Implement Trie (Prefix Tree)
3. Design Circular Queue

Union Find (Disjoint Set):

1. Friend Circles
2. Accounts Merge
3. Surrounded Regions
4. Redundant Connection

Trie:

1. Add and Search Word — Data structure design
2. Word Search II
3. Replace Words
4. Implement Magic Dictionary

Heap (Priority Queue):

1. Merge k Sorted Lists
2. Top K Frequent Elements
3. Find Median from Data Stream
4. Ugly Number II

Topological Sort:

1. Course Schedule
2. Alien Dictionary
3. Sequence Reconstruction
4. Reconstruct Itinerary
5. Course Schedule II

Breadth-First Search (BFS):

1. Word Ladder
2. Binary Tree Level Order Traversal
3. Minimum Genetic Mutation

Depth-First Search (DFS):

1. Binary Tree Paths
2. Flatten Binary Tree to Linked List
3. Word Break
4. Remove Invalid Parentheses
5. All Paths From Source to Target

Segment Tree:

1. Range Sum Query — Mutable
2. Count of Range Sum
3. The Skyline Problem
4. Range Minimum Query (RMQ)

Fenwick Tree (Binary Indexed Tree):

1. Reverse Pairs
2. Range Sum Query 2D — Mutable

Linked List Manipulation:

1. Swap Nodes in Pairs

Tree Traversals:

1. Binary Tree Preorder Traversal
2. Binary Tree Inorder Traversal
3. Binary Tree Postorder Traversal
4. N-ary Tree Preorder Traversal
5. N-ary Tree Postorder Traversal
6. Lowest Common Ancestor of a Binary Search Tree

Geometry:

1. Valid Square
2. K Closest Points to Origin
3. Number of Boomerangs
4. Convex Hull
5. Max Points on a Line

Good luck on your job preparation and coding interviews!