First non-repeating character

Medium 30 pts New · no attempts yet csharp

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Find first non-repeating char in "swiss" (answer: w).

Static hints

Use Dictionary or LINQ GroupBy for frequencies.

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Official solution

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        string s = "swiss";
        var freq = s.GroupBy(c => c).ToDictionary(g => g.Key, g => g.Count());
        char result = s.First(c => freq[c] == 1);
        Console.WriteLine(result);
    }
}

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Explanation

Frequency map then scan original string for count==1—common Amazon/Google style question.

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First non-repeating character

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