Striver’s SDE Sheet

SDE Sheet contains very handily crafted and picked top coding interview questions from different topics of Data Structures & Algorithms. These questions are one of the most asked coding interview questions in coding interviews of companies like Google, Amazon, Microsoft, Facebook, Swiggy, Flipkart, etc, and cover almost all of the concepts related to Data Structure & Algorithms.

Azhar Khan122 problems28 Easy55 Med17 Hard

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Title	Solution	Practice	Difficulty	Companies	Topics
208. Implement Trie (Prefix Tree)	Solution	Solve	Medium	-	Design Hash Table+2
421. Maximum XOR of Two Numbers in an Array	Solution	Solve	Medium	-	Array Bit Manipulation+2
1707. Maximum XOR With an Element From Array	Solution	Solve	Hard	-	Array Bit Manipulation+1
139. Word Break	Solution	Solve	Medium	-	Array Dynamic Programming+4
322. Coin Change	Solution	Solve	Medium	-	Array Breadth-First Search+1
416. Partition Equal Subset Sum	Solution	Solve	Medium	-	Array Dynamic Programming
1547. Minimum Cost to Cut a Stick	Solution	Solve	Hard	-	Array Dynamic Programming+1
64. Minimum Path Sum	Solution	Solve	Medium	-	Array Dynamic Programming+1
72. Edit Distance	Solution	Solve	Medium	-	Dynamic Programming String
1143. Longest Common Subsequence	Solution	Solve	Medium	-	Dynamic Programming String
152. Maximum Product Subarray	Solution	Solve	Medium	-	Array Dynamic Programming
300. Longest Increasing Subsequence	Solution	Solve	Medium	-	Array Binary Search+1
1520. Maximum Number of Non-Overlapping Substrings	Solution	Solve	Hard	-	Greedy String
785. Is Graph Bipartite?	Solution	Solve	Medium	-	Breadth-First Search Depth-First Search+2
133. Clone Graph	Solution	Solve	Medium	-	Breadth-First Search Depth-First Search+2
200. Number of Islands	Solution	Solve	Medium	-	Array Breadth-First Search+3
207. Course Schedule	Solution	Solve	Medium	-	Breadth-First Search Depth-First Search+2
733. Flood Fill	Solution	Solve	Easy	-	Array Breadth-First Search+2
173. Binary Search Tree Iterator	Solution	Solve	Medium	-	Binary Search Tree Binary Tree+4
297. Serialize and Deserialize Binary Tree	Solution	Solve	Hard	-	Binary Tree Breadth-First Search+4
703. Kth Largest Element in a Stream	Solution	Solve	Easy	-	Binary Search Tree Binary Tree+4
1373. Maximum Sum BST in Binary Tree	Solution	Solve	Hard	-	Binary Search Tree Binary Tree+3
230. Kth Smallest Element in a BST	Solution	Solve	Medium	-	Binary Search Tree Binary Tree+2
235. Lowest Common Ancestor of a Binary Search Tree	Solution	Solve	Medium	-	Binary Search Tree Binary Tree+2
653. Two Sum IV - Input is a BST	Solution	Solve	Easy	-	Binary Search Tree Binary Tree+5
98. Validate Binary Search Tree	Solution	Solve	Medium	-	Binary Search Tree Binary Tree+2
108. Convert Sorted Array to Binary Search Tree	Solution	Solve	Easy	-	Array Binary Search Tree+3
700. Search in a Binary Search Tree	Solution	Solve	Easy	-	Binary Search Tree Binary Tree+1
1008. Construct Binary Search Tree from Preorder Traversal	Solution	Solve	Medium	-	Array Binary Search Tree+4
116. Populating Next Right Pointers in Each Node	Solution	Solve	Medium	-	Binary Tree Breadth-First Search+3
101. Symmetric Tree	Solution	Solve	Easy	-	Binary Tree Breadth-First Search+2
114. Flatten Binary Tree to Linked List	Solution	Solve	Medium	-	Binary Tree Depth-First Search+3
105. Construct Binary Tree from Preorder and Inorder Traversal	Solution	Solve	Medium	-	Array Binary Tree+3
106. Construct Binary Tree from Inorder and Postorder Traversal	Solution	Solve	Medium	-	Array Binary Tree+3
124. Binary Tree Maximum Path Sum	Solution	Solve	Hard	-	Binary Tree Depth-First Search+2
545. Boundary of Binary Tree	Solution	Solve	Medium	-	Binary Tree Depth-First Search+1
100. Same Tree	Solution	Solve	Easy	-	Binary Tree Breadth-First Search+2
103. Binary Tree Zigzag Level Order Traversal	Solution	Solve	Medium	-	Binary Tree Breadth-First Search+1
236. Lowest Common Ancestor of a Binary Tree	Solution	Solve	Medium	-	Binary Tree Depth-First Search+1
104. Maximum Depth of Binary Tree	Solution	Solve	Easy	-	Binary Tree Breadth-First Search+2
110. Balanced Binary Tree	Solution	Solve	Easy	-	Binary Tree Depth-First Search+1
543. Diameter of Binary Tree	Solution	Solve	Easy	-	Binary Tree Depth-First Search+1
102. Binary Tree Level Order Traversal	Solution	Solve	Medium	-	Binary Tree Breadth-First Search+1
662. Maximum Width of Binary Tree	Solution	Solve	Medium	-	Binary Tree Breadth-First Search+2
987. Vertical Order Traversal of a Binary Tree	Solution	Solve	Hard	-	Binary Tree Breadth-First Search+4
94. Binary Tree Inorder Traversal	Solution	Solve	Easy	-	Binary Tree Depth-First Search+2
144. Binary Tree Preorder Traversal	Solution	Solve	Easy	-	Binary Tree Depth-First Search+2
145. Binary Tree Postorder Traversal	Solution	Solve	Easy	-	Binary Tree Depth-First Search+2
38. Count and Say	Solution	Solve	Medium	-	String
165. Compare Version Numbers	Solution	Solve	Medium	-	String Two Pointers
242. Valid Anagram	Solution	Solve	Easy	-	Hash Table Sorting+1
8. String to Integer (atoi)	Solution	Solve	Medium	-	String
14. Longest Common Prefix	Solution	Solve	Easy	-	String Trie
28. Find the Index of the First Occurrence in a String	Solution	Solve	Easy	-	String String Matching+1
686. Repeated String Match	Solution	Solve	Medium	-	String String Matching
5. Longest Palindromic Substring	Solution	Solve	Medium	-	Dynamic Programming String+1
13. Roman to Integer	Solution	Solve	Easy	-	Hash Table Math+1
151. Reverse Words in a String	Solution	Solve	Medium	-	String Two Pointers
277. Find the Celebrity	Solution	Solve	Medium	-	Graph Interactive+1
901. Online Stock Span	Solution	Solve	Medium	-	Data Stream Design+2
994. Rotting Oranges	Solution	Solve	Medium	-	Array Breadth-First Search+1
155. Min Stack	Solution	Solve	Medium	-	Design Stack
84. Largest Rectangle in Histogram	Solution	Solve	Hard	-	Array Monotonic Stack+1
146. LRU Cache	Solution	Solve	Medium	-	Design Doubly-Linked List+2
239. Sliding Window Maximum	Solution	Solve	Hard	-	Array Heap (Priority Queue)+3
460. LFU Cache	Solution	Solve	Hard	-	Design Doubly-Linked List+2
20. Valid Parentheses	Solution	Solve	Easy	-	Stack String
225. Implement Stack using Queues	Solution	Solve	Easy	-	Design Queue+1
232. Implement Queue using Stacks	Solution	Solve	Easy	-	Design Queue+1
496. Next Greater Element I	Solution	Solve	Easy	-	Array Hash Table+2
215. Kth Largest Element in an Array	Solution	Solve	Medium	-	Array Divide and Conquer+3
295. Find Median from Data Stream	Solution	Solve	Hard	-	Data Stream Design+3
347. Top K Frequent Elements	Solution	Solve	Medium	-	Array Bucket Sort+6
4. Median of Two Sorted Arrays	Solution	Solve	Hard	-	Array Binary Search+1
33. Search in Rotated Sorted Array	Solution	Solve	Medium	-	Array Binary Search
37. Sudoku Solver	Solution	Solve	Hard	-	Array Backtracking+2
540. Single Element in a Sorted Array	Solution	Solve	Medium	-	Array Binary Search
51. N-Queens	Solution	Solve	Hard	-	Array Backtracking
40. Combination Sum II	Solution	Solve	Medium	-	Array Backtracking
46. Permutations	Solution	Solve	Medium	-	Array Backtracking
60. Permutation Sequence	Solution	Solve	Hard	-	Math Recursion
131. Palindrome Partitioning	Solution	Solve	Medium	-	Backtracking Dynamic Programming+1
39. Combination Sum	Solution	Solve	Medium	-	Array Backtracking
90. Subsets II	Solution	Solve	Medium	-	Array Backtracking+1
455. Assign Cookies	Solution	Solve	Easy	-	Array Greedy+2
485. Max Consecutive Ones	Solution	Solve	Easy	-	Array
15. 3Sum	Solution	Solve	Medium	-	Array Sorting+1
26. Remove Duplicates from Sorted Array	Solution	Solve	Easy	-	Array Two Pointers
42. Trapping Rain Water	Solution	Solve	Hard	-	Array Dynamic Programming+3
61. Rotate List	Solution	Solve	Medium	-	Linked List Two Pointers
138. Copy List with Random Pointer	Solution	Solve	Medium	-	Hash Table Linked List
142. Linked List Cycle II	Solution	Solve	Medium	-	Hash Table Linked List+1
234. Palindrome Linked List	Solution	Solve	Easy	-	Linked List Recursion+2
25. Reverse Nodes in k-Group	Solution	Solve	Hard	-	Linked List Recursion
141. Linked List Cycle	Solution	Solve	Easy	-	Hash Table Linked List+1
160. Intersection of Two Linked Lists	Solution	Solve	Easy	-	Hash Table Linked List+1
2. Add Two Numbers	Solution	Solve	Medium	-	Linked List Math+1
19. Remove Nth Node From End of List	Solution	Solve	Medium	-	Linked List Two Pointers
237. Delete Node in a Linked List	Solution	Solve	Medium	-	Linked List
21. Merge Two Sorted Lists	Solution	Solve	Easy	-	Linked List Recursion

#208

Implement Trie (Prefix Tree)

Medium✓ Solution

Striver’s SDE Sheet

Implement Trie (Prefix Tree)

Maximum XOR of Two Numbers in an Array

Maximum XOR With an Element From Array

Word Break

Coin Change

Partition Equal Subset Sum

Minimum Cost to Cut a Stick

Minimum Path Sum

Edit Distance

Longest Common Subsequence

Maximum Product Subarray

Longest Increasing Subsequence

Maximum Number of Non-Overlapping Substrings

Is Graph Bipartite?

Clone Graph

Number of Islands

Course Schedule

Flood Fill

Binary Search Tree Iterator

Serialize and Deserialize Binary Tree

Kth Largest Element in a Stream

Maximum Sum BST in Binary Tree

Kth Smallest Element in a BST

Lowest Common Ancestor of a Binary Search Tree

Two Sum IV - Input is a BST

Validate Binary Search Tree

Convert Sorted Array to Binary Search Tree

Search in a Binary Search Tree

Construct Binary Search Tree from Preorder Traversal

Populating Next Right Pointers in Each Node

Symmetric Tree

Flatten Binary Tree to Linked List

Construct Binary Tree from Preorder and Inorder Traversal

Construct Binary Tree from Inorder and Postorder Traversal

Binary Tree Maximum Path Sum

Boundary of Binary Tree

Same Tree

Binary Tree Zigzag Level Order Traversal

Lowest Common Ancestor of a Binary Tree

Maximum Depth of Binary Tree

Balanced Binary Tree

Diameter of Binary Tree

Binary Tree Level Order Traversal

Maximum Width of Binary Tree

Vertical Order Traversal of a Binary Tree

Binary Tree Inorder Traversal

Binary Tree Preorder Traversal

Binary Tree Postorder Traversal

Count and Say

Compare Version Numbers

Valid Anagram

String to Integer (atoi)

Longest Common Prefix

Find the Index of the First Occurrence in a String

Repeated String Match

Longest Palindromic Substring

Roman to Integer

Reverse Words in a String

Find the Celebrity

Online Stock Span

Rotting Oranges

Min Stack

Largest Rectangle in Histogram

LRU Cache

Sliding Window Maximum

LFU Cache

Valid Parentheses

Implement Stack using Queues

Implement Queue using Stacks

Next Greater Element I

Kth Largest Element in an Array

Find Median from Data Stream

Top K Frequent Elements

Median of Two Sorted Arrays

Search in Rotated Sorted Array

Sudoku Solver

Single Element in a Sorted Array

N-Queens

Combination Sum II