SingleNumber.cpp

/*
Single Number
Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Example :
Input : [1 2 2 3 1]
Output : 3
*/

int Solution::singleNumber(const vector<int> &A) {
    int t=A[0];
    for(int i=1;i<A.size();i++){
        t^=A[i];
    }
    return t;
}