题目描述

blablabla

样例

blablabla

算法1

(一次遍历) $O(n)$

blablabla

时间复杂度分析：0(n)

C++ 代码

class Solution {
public:
    int findNumberAppearingOnce(vector<int>& nums) {
        int length = nums.size();
        if (length == 0) return -1;
        int bitsum[32] = {0};
        for (int i = 0; i < length; i++){
            int bitmask = 1;
            for (int j = 31; j >= 0; j-- ){
                bitsum[j] += (nums[i] & bitmask)?1 : 0;
                bitmask = bitmask << 1;
                }
            }
        int result = 0;
        for (int i = 0; i < 32; i++) {
            result = result << 1;
            result += bitsum[i]%3;
            //result = result << 1;
            }   
        return result;
    }
};