# 476. Number Complement

476. Number Complement

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Note:
The given integer is guaranteed to fit within the range of a 32-bit signed integer.
You could assume no leading zero bit in the integer’s binary representation.
Example 1:
Input: 5
Output: 2
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
Example 2:
Input: 1
Output: 0
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.

```int findComplement(int num) {
int bits, pos = 0;
int res = 0, i;

while (0 != num) {
bits[pos++] = num & 1;
num >>= 1;
}

for (i = 0; i < pos; ++i) {
res += (bits[i] ^ 1) * (1UL << i);
}

return res;
}

```

```int findComplement(int num) {
int i, res = 0;

for (i = 0; i < 31; ++i) {
if ((1UL << i) > num)break;
if (0 == ((1UL << i) & num))
res |= (1UL << i);
}
return res;
}```