← DSA Practice Essential 75 Based on the widely-recommended Blind 75 LeetCode list. Each problem includes hints, approach guides, and optimal solutions in Python, Java, C++, and JavaScript.
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Array 10 Foundation problems covering hash maps, two pointers, sliding window, and binary search on arrays.
Array Hash Table Google Amazon Meta Microsoft +2 more
#121 Best Time to Buy and Sell Stock
Easy Solve Array Dynamic Programming Amazon Meta Goldman Sachs Microsoft
Array Hash Table Sorting Amazon Apple Adobe
#238 Product of Array Except Self
Medium Solve Array Amazon Meta Microsoft Apple
Array Dynamic Programming Divide and Conquer Amazon Microsoft LinkedIn Apple +1 more
#152 Maximum Product Subarray
Medium Solve Array Dynamic Programming Amazon Google Microsoft LinkedIn
#153 Find Minimum in Rotated Sorted Array
Medium Solve Array Binary Search Amazon Meta Microsoft Bloomberg
#33 Search in Rotated Sorted Array
Medium Solve Array Binary Search Amazon Meta Microsoft LinkedIn +1 more
Array Two Pointers Sorting Amazon Meta Microsoft Bloomberg +1 more
#11 Container With Most Water
Medium Solve Array Two Pointers Greedy Amazon Meta Google Microsoft +1 more
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Binary 5 Bit manipulation techniques including XOR tricks, bit counting, and bitwise arithmetic.
Bit Manipulation Math Meta Amazon
Bit Manipulation Microsoft Apple
Bit Manipulation Dynamic Programming Amazon Adobe
Array Bit Manipulation Math Amazon Microsoft Bloomberg
Bit Manipulation Apple Amazon
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Dynamic Programming 11 Classic DP patterns: climbing stairs, knapsack variants, sequence problems, and grid traversal.
Dynamic Programming Math Amazon Google Microsoft Adobe
Array Dynamic Programming Amazon Google Microsoft Bloomberg
#300 Longest Increasing Subsequence
Medium Solve Array Dynamic Programming Binary Search Google Amazon Microsoft
#1143 Longest Common Subsequence
Medium Solve String Dynamic Programming Amazon Google
String Dynamic Programming Hash Table Amazon Meta Bloomberg Microsoft +1 more
Array Dynamic Programming Google Meta
Array Dynamic Programming Amazon Google Microsoft Cisco
Array Dynamic Programming Amazon Google
String Dynamic Programming Meta Amazon Goldman Sachs Microsoft
Math Dynamic Programming Amazon Google Meta Bloomberg
Array Dynamic Programming Greedy Amazon Microsoft Bloomberg
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Graph 8 Graph traversal, cycle detection, topological sort, union-find, and connected components.
Graph DFS BFS Hash Table Meta Amazon Google Microsoft
Graph DFS BFS Amazon Meta Microsoft Google
#417 Pacific Atlantic Water Flow
Medium Solve Array Matrix DFS BFS Google Amazon
Array Matrix DFS BFS Union Find Amazon Meta Google Microsoft +1 more
#128 Longest Consecutive Sequence
Medium Solve Array Hash Table Union Find Amazon Google Meta Microsoft
#269 Alien Dictionary Premium
Hard Solve Graph DFS BFS Sorting Meta Amazon Google Airbnb +1 more
#261 Graph Valid Tree Premium
Medium Solve Graph DFS BFS Union Find Google Amazon Meta
#323 Number of Connected Components in an Undirected Graph Premium
Medium Solve Graph DFS BFS Union Find Google Amazon Meta LinkedIn
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Interval 5 Interval merging, insertion, scheduling, and overlap detection problems.
Array Interval Google Amazon Meta LinkedIn
Array Sorting Interval Amazon Meta Google Microsoft +1 more
#435 Non-overlapping Intervals
Medium Solve Array Sorting Greedy Interval Amazon Meta
Array Sorting Interval Amazon Meta Bloomberg
#253 Meeting Rooms II Premium
Medium Solve Array Sorting Heap Interval Amazon Meta Google Bloomberg +1 more
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Linked List 6 Pointer manipulation, reversal, cycle detection, merging, and two-pointer techniques on linked lists.
Linked List Recursion Amazon Microsoft Apple Bloomberg
Linked List Two Pointers Amazon Microsoft Bloomberg
#21 Merge Two Sorted Lists
Easy Solve Linked List Recursion Amazon Microsoft Apple Bloomberg
Linked List Heap Divide and Conquer Sorting Amazon Meta Google Microsoft +1 more
#19 Remove Nth Node From End of List
Medium Solve Linked List Two Pointers Amazon Meta Microsoft
Linked List Two Pointers Amazon Meta Microsoft Bloomberg
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Matrix 4 2D array traversal patterns including spiral order, rotation, and backtracking search.
Array Matrix Hash Table Amazon Meta Microsoft
Array Matrix Amazon Microsoft Apple Goldman Sachs
Array Matrix Math Amazon Microsoft Apple Google
Array Matrix Backtracking Amazon Microsoft Bloomberg Intuit
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String 10 Sliding window, two pointers, anagram detection, palindromes, and encoding problems.
#3 Longest Substring Without Repeating Characters
Medium Solve String Hash Table Sliding Window Amazon Meta Microsoft Bloomberg +1 more
#424 Longest Repeating Character Replacement
Medium Solve String Hash Table Sliding Window Google Amazon
#76 Minimum Window Substring
Hard Solve String Hash Table Sliding Window Meta Amazon Google LinkedIn +1 more
String Hash Table Sorting Amazon Microsoft Bloomberg
Array String Hash Table Sorting Amazon Meta Microsoft Bloomberg
String Stack Amazon Meta Microsoft Bloomberg +1 more
String Two Pointers Meta Amazon Microsoft
#5 Longest Palindromic Substring
Medium Solve String Dynamic Programming Two Pointers Amazon Microsoft Meta Goldman Sachs
#647 Palindromic Substrings
Medium Solve String Dynamic Programming Two Pointers Meta Amazon Goldman Sachs
#271 Encode and Decode Strings Premium
Medium Solve Array String Design Google Meta Amazon
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Tree 14 Binary tree traversal, BST properties, serialization, tries, and recursive tree algorithms.
#104 Maximum Depth of Binary Tree
Easy Solve Binary Tree DFS BFS Recursion Amazon Microsoft Google
Binary Tree DFS Recursion Amazon Microsoft Bloomberg
Binary Tree DFS BFS Recursion Google Amazon Microsoft
#124 Binary Tree Maximum Path Sum
Hard Solve Binary Tree DFS Dynamic Programming Meta Amazon Google Microsoft
#102 Binary Tree Level Order Traversal
Medium Solve Binary Tree BFS Amazon Meta Microsoft Bloomberg
#297 Serialize and Deserialize Binary Tree
Hard Solve Binary Tree DFS BFS Design String Meta Amazon Microsoft Google +1 more
#572 Subtree of Another Tree
Easy Solve Binary Tree DFS Recursion Amazon Meta Microsoft
#105 Construct Binary Tree from Preorder and Inorder Traversal
Medium Solve Binary Tree DFS Hash Table Recursion Amazon Meta Microsoft Google
#98 Validate Binary Search Tree
Medium Solve Binary Tree BST DFS Recursion Amazon Meta Microsoft Bloomberg
#230 Kth Smallest Element in a BST
Medium Solve Binary Tree BST DFS Amazon Meta Microsoft
#235 Lowest Common Ancestor of a Binary Search Tree
Medium Solve Binary Tree BST DFS Meta Amazon Microsoft LinkedIn
Trie Design String Hash Table Amazon Google Microsoft
#211 Design Add and Search Words Data Structure
Medium Solve Trie Design String DFS Backtracking Meta Amazon
Array Matrix Trie Backtracking DFS Amazon Microsoft Google Uber
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Heap 2 Priority queue problems including top-k elements and streaming median.
#347 Top K Frequent Elements
Medium Solve Array Hash Table Heap Sorting Amazon Meta Google Microsoft
#295 Find Median from Data Stream
Hard Solve Heap Design Sorting Amazon Google Meta Microsoft +1 more