Single Number II

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

#include<iostream>#include<unordered_map>#include<vector>using namespace std;#define STOP system("pause")#if 0class Solution {public:int singleNumber(int A[], int n) {unordered_map<int ,int> hash_map;for (int i = 0; i < n; i++){++hash_map[A[i]];if (hash_map[A[i]] == 3) hash_map.erase(A[i]);}return hash_map.begin()->first;}};#elif 1class Solution {public :int singleNumber(int A[], int n){vector<int> bit_num(32, 0);for (int i = 0; i < n; i++){for (int j = 0; j < 32; j++){if (A[i] & 1 << j)bit_num[j]++;}}int res = 0;for (int i = 0; i < 32; i++)res += (bit_num[i] % 3) << i;return res;}};#endif void test0(){int A[] = { 1, 2, 3, 1, 2, 3, 1, 2, 3, 6 };Solution ss;int res = ss.singleNumber(A,10);if (res != 6)printf("error");elseprintf("passed");}int main(){test0();STOP;return 0;}