15 Jun 2024•C++ / Python / TypeScript•Easy

First Unique Character in a String

Collected C++, Python, TypeScript solutions for first unique character in a string. Add a dedicated write-up later if you want deeper notes.

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auto-generated entry for First Unique Character in a String. the solution files are available below.

solution files

C++ first-unique-character-in-a-string/synced-solution.cpp
Python first-unique-character-in-a-string/synced-solution.py
TypeScript first-unique-character-in-a-string/synced-solution.ts

Solution files

Python•first-unique-character-in-a-string/synced-solution.py

def firstUniqChar(s):
    from collections import Counter

    char_count = Counter(s)

    for i, char in enumerate(s):
        if char_count[char] == class="syntax-number">1:
            return i

    return -class="syntax-number">1

C++•first-unique-character-in-a-string/synced-solution.cpp

class Solution {
public:
    int firstUniqChar(string s) {
        unordered_map<char, int> count;

        for (char c : s) {
            count[c]++;
        }

        for (int i = class="syntax-number">0; i < s.length(); i++) {
            if (count[s[i]] == class="syntax-number">1) {
                return i;
            }
        }

        return -class="syntax-number">1;
    }
};

TypeScript•first-unique-character-in-a-string/synced-solution.ts

function firstUniqChar(s: string): number {
    const count = new Map<string, number>();

    for (const char of s) {
        count.set(char, (count.get(char) || class="syntax-number">0) + class="syntax-number">1);
    }

    for (let i = class="syntax-number">0; i < s.length; i++) {
        if (count.get(s[i]) === class="syntax-number">1) {
            return i;
        }
    }

    return -class="syntax-number">1;
}