Introduction

In this blog post, we will explore how to solve the LeetCode problem "1009" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

The complement of an integer is the integer you get when you flip all the 0's to 1's and all the 1's to 0's in its binary representation. For example, The integer 5 is "101" in binary and its complement is "010" which is the integer 2. Given an integer n, return its complement. Example 1: Input: n = 5 Output: 2 Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10. Example 2: Input: n = 7 Output: 0 Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10. Example 3: Input: n = 10 Output: 5 Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10. Constraints: 0 <= n < 109 Note: This question is the same as 476: https://leetcode.com/problems/number-complement/

Explanation

Here's the breakdown of the problem and the solution:

• High-Level Approach:

  • Find the number of bits required to represent the integer n in binary.
  • Create a mask with all bits set to 1, having the same number of bits as n.
  • Calculate the complement by XORing n with the mask.

• Complexity Analysis:

  • Runtime Complexity: O(1) - The number of iterations in the while loop is bounded by the maximum number of bits in an integer (which is a constant). The XOR operation is also O(1).
  • Storage Complexity: O(1) - Only a few integer variables are used.

Code

    class Solution:
    def findComplement(self, num: int) -> int:
        """
        Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

        Args:
            num: A positive integer.

        Returns:
            The complement number of the input integer.
        """
        # Find the number of bits required to represent the integer n in binary.
        bit_count = 0
        n = num
        while n > 0:
            n >>= 1
            bit_count += 1

        # Create a mask with all bits set to 1, having the same number of bits as n.
        mask = (1 << bit_count) - 1

        # Calculate the complement by XORing n with the mask.
        return num ^ mask