分析:所有元素异或,最终结果就是出现一次的数
class Solution {
public:
int singleNumber(int A[], int n) {
// Note: The Solution object is instantiated only once and is reused by each test case.
int res = 0;
for(int i = 0; i < n; i++)
res = res^A[i];
return res;
}
};