README.md

2429. Minimize XOR

Given two positive integers num1 and num2, find the positive integer x such that:

• x has the same number of set bits as num2, and
• The value x XOR num1 is minimal.

Note that XOR is the bitwise XOR operation.

Return the integer x. The test cases are generated such that x is uniquely determined.

The number of set bits of an integer is the number of 1's in its binary representation.

Example 1:

Input: num1 = 3, num2 = 5
Output: 3
Explanation:
The binary representations of num1 and num2 are 0011 and 0101, respectively.
The integer 3 has the same number of set bits as num2, and the value 3 XOR 3 = 0 is minimal.

Example 2:

Input: num1 = 1, num2 = 12
Output: 3
Explanation:
The binary representations of num1 and num2 are 0001 and 1100, respectively.
The integer 3 has the same number of set bits as num2, and the value 3 XOR 1 = 2 is minimal.

Constraints:

• 1 <= num1, num2 <= 109

Solutions (Rust)

1. Solution

impl Solution {
    pub fn minimize_xor(num1: i32, num2: i32) -> i32 {
        let ones1 = num1.count_ones() as i32;
        let ones2 = num2.count_ones() as i32;
        let mut i = 0;
        let mut x = num1;

        for _ in 0..(ones1 - ones2).max(ones2 - ones1) {
            if ones1 > ones2 {
                while x & (1 << i) == 0 {
                    i += 1;
                }

                x ^= 1 << i;
            } else {
                while x & (1 << i) != 0 {
                    i += 1;
                }

                x |= 1 << i;
            }
        }

        x
    }
}