LeetCode137——Single Number II

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?

难度系数：

中等

实现

这题要线性时间，不使用额外存储，我觉得挺难的，我没做出来，看来网上的答案。方法很好，理解后也不是很难，只是之前没 做过类似的，估计不容易想出来。

[code]int singleNumber(int A[], int n) {
    int one = 0, two = 0, three = 0;
    for (int i = 0; i < n; ++i) {
        three = two & A[i];
        two |= one & A[i];
        one |= A[i];
        one ^= three;
        two ^= three;
    }
    return one;
}