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tags: data_structure_python
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# Number complement <img src="https://img.shields.io/badge/-easy-brightgreen">

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: https://leetcode.com/problems/complement-of-base-10-integer/

# Solution

class Solution:
    def findComplement(self, num: int) -> int:
        nb_ones = len(bin(num)[2:])
        ones = '1' * nb_ones
        
        return num ^ int(ones, 2)