[LeetCode] [Single Number II 2013-10-02]

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?

class Solution {
public:
int bitCheck[32];

int singleNumber(int A[], int n) {
for(int d =0;d < 32 ;d++)
{
bitCheck[d] = 0;
}

for(int i = 0 ;i < n ;i++)
{
int tmp = A[i];
for(int d = 0; d < 32 ;d++)
{
int t = tmp&(1<<d);
if(t != 0)
{
bitCheck[d]++;
if(bitCheck[d] == 3)
{
bitCheck[d] = 0;
}
}
}
}

int s = 0;
for(int d = 0; d<32 ;d++)
{
s = s + bitCheck[d]*(1<<d);
}
return s;

}
};