137. Single Number II

/*

Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one.

Note:

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Example 1:

Input: [2,2,3,2]
Output: 3
Example 2:

Input: [0,1,0,1,0,1,99]
Output: 99




*/
public class Solution {
    public int SingleNumber(int[] nums) {
          int number = 0;
        var hash = new Dictionary<int,int>();
        foreach(int i in nums){
            if(hash.ContainsKey(i)){
                
                hash[i]++;
            }
            else{
                hash.Add(i,1);
            }
            
        }
        
        foreach(var i in hash){
           if(i.Value == 1)
        number = i.Key;
        }
        return number;
    }
}