[Leetcode] Single Number 1 & 2

Single Number

 

AC Rate: 1243/2713

My Submissions

 

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?

 

class Solution {
public:
    int singleNumber(int A[], int n) {
        if (n == 0) return 0;
        int x = A[0];
        for (int i = 1; i < n; i++) x^=A[i];
        return x;
    }
};

Single Number II

 

AC Rate: 657/2247

My Submissions

 

Given an array of integers, every element appears three times except for one. Find that single one.

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

class Solution {
public:
    int singleNumber(int A[], int n) {
        int x[32];
        memset(x, 0, sizeof(x));
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < 32; j++) {
                x[j] += (A[i] >> j) & (1);
                x[j] %= 3;
            }
        }
        int res = 0;
        for (int i = 0; i < 32; i++) {
            res += (x[i] << i);
        }
        return res;
    }
};