Finding an element in an array where every element is repeated odd number of times (but more than single occurrence) and only one appears once

Question

You have an array in which every number is repeated odd number of times (but more than single occurrence). Exactly one number appears once. How do you find the number that a

Answer 1

Test Score 100% with c#

using System;
using System.Collections.Generic;
// you can also use other imports, for example:
// using System.Collections.Generic;

// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");

class Solution {
    public int solution(int[] A) {

        Dictionary dic =new Dictionary();

        foreach(int i in A)
        {
            if (dic.ContainsKey(i))
            {
                dic[i]=dic[i]+1;                
            }
            else
            {
                dic.Add(i, 1);                
            }
        }

        foreach(var d in dic)
        {
            if (d.Value%2==1)
            {
                 return d.Key;
            }
        }

        return -1;
    }
}