LeetCode 476. Number Complement

Description

https://leetcode.com/problems/number-complement/

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/

Explanation

Find the binary string and then convert it to complement number’s binary string. Finally convert back to 10 base integer.

Python Solution

class Solution:
    def findComplement(self, num: int) -> int:
        binary = bin(num)[2:]
        
        result = ""
        for bit in binary:

            if bit == "1":
                result += "0"
            else:
                result += "1"

            
        return int(result, 2)