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

扩展2进制亦或的定义到三进制

class Solution {
    public int singleNumber(int[] nums) {
        int result = 0;
        for(int i = 0 ;i<32;i++)
        {
            int mask=1<<i;
            int  count=0;
            for(int j = 0 ;j<nums.length;j++)
            {
                int val = nums[j]&mask;
                if(val==mask)
                    count++;
            }
            count=(count%3)<<i;
            result=count|result;
        }
        return result;
    }
}