[LeetCode] 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?

public class Solution {
public int singleNumber(int[] A) {
int ones = 0, twos = 0, threes = 0;
for(int i = 0; i < A.length; i++)
{
threes = twos & A[i];
twos = twos | ones & A[i];
ones = ones | A[i];

twos = twos & ~threes;
ones = ones & ~threes;
}
return ones;
}
}