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) {
// Note: The Solution object is instantiated only once and is reused by each test case.
if(A.length == 0)
return 0;
int[] cnt = new int[32];
for(int i = 0; i < A.length; i++)
{
for(int j = 0; j < 32; j++)
{
if( (A[i]>>j & 1) ==1)
{
cnt[j] = (cnt[j] + 1)%3;
}
}
}
int res = 0;
for(int i = 0; i < 32; i++)
{
res += (cnt[i] << i);
}
cnt = null;
return res;
}
}