Array + HashMap

Engineering Articles & Deep Dives

Array + HashMap Pattern and most asked problems like Two Sum, Group Anagrams, and Longest Consecutive Sequence.

All Array / String Array + HashMap Sliding Window Two Pointer Linked List Binary Search Stack Matrix Trees DFS/BFS + BST Backtracking Heap and Priority Queue Graph + Topological Sort Dynamic Programming Prefix Sum Greedy Interval Divide and Conquer Union-Find (Disjoint Set Union) Trie Bit Manipulation Math / Number Theory
Array + HashMap
Two Sum [Easy]
15 Aug 2026 2 min read
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Array + HashMap
Valid Anagram [Easy]
30 Aug 2026 2 min read
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Array + HashMap
First Unique Character in a String [Easy]
15 Aug 2026 2 min read
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Array + HashMap
Find the Difference of Two Arrays [Easy]
20 Sep 2026 2 min read
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Array + HashMap
Unique Number of Occurrences [Easy]
20 Sep 2026 2 min read
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Array + HashMap
Group Anagrams [Medium]
20 Sep 2026 2 min read
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Array + HashMap
Determine if Two Strings Are Close [Medium]
20 Sep 2026 2 min read
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Array + HashMap
Valid Sudoku [Medium]
22 Sep 2026 2 min read
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Array + HashMap
Longest Consecutive Sequence [Medium]
20 Sep 2026 3 min read
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