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First Unique Character in a String

easy Solve on LeetCode

Last edited: August 2, 2025

Problem
Examples
Solution
Method 1 - Brute Force
Method 2 - Two Pass - Use Hashset/HashMap/Array Indices
Using Count or Freq Array
Using Hashmap
Method 3 - Using LinkedHashmap and Set with One Pass 🏆
Method 4 - Traversing String Only Once Storing char’s First Index
Method 5 - Using lastIndexOf

Related Tags

array-algo counting duplicates-algo hash-table leetcode non-duplicated-algo repeat string string-algo

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