Single Number II.cpp

/* 

    Solution by Rahul Surana
    
    ***********************************************************

Given an integer array nums where every element appears three times except for one, which appears exactly once. 
Find the single element and return it.

You must implement a solution with a linear runtime complexity and use only constant extra space.


    ***********************************************************
*/


class Solution {
public:
    int singleNumber(vector<int>& nums) {
        unordered_map<int,int> m;
        for(auto x: nums){
            m[x]++;
        }
        for(auto z: m) if(z.second ==1) return z.first;
        return -1;
    }
};