387. First Unique Character in a String

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Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1. Example 1: Input: s = "leetcode" Output: 0 Explanation: The character 'l' at index 0 is the first character that does not occur at any other index. Example 2: Input: s = "loveleetcode" Output: 2 Example 3: Input: s = "aabb" Output: -1 Constraints: - 1 <= s.length <

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solution.cppC++17

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