Cloudera

2020-10-03

## 476. Number Complement

### Question:

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

#### Example 1:

``````Input: num = 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: num = 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.
``````

Constraints:

• The given integer `num` is guaranteed to fit within the range of a 32-bit signed integer.
• `num >= 1`
• You could assume no leading zero bit in the integer’s binary representation.
• This question is the same as 1009: LeetCode Question 1009

### Solution:

Using XOR(^) to compare each digit with 1.

``````class Solution {
public int bitwiseComplement(int N) {
if (N == 0) return 1;
if (N == 1) return 0;
int orBit = 1;
int rest = N;
while (rest != 0) {
N ^= orBit;
orBit <<= 1;
rest >>= 1;
}
return N;
}
}
``````