README.md

201. Bitwise AND of Numbers Range

Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.

Example 1:

Input: [5,7]
Output: 4

Example 2:

Input: [0,1]
Output: 0

Solutions (Rust)

1. Solution

impl Solution {
    pub fn range_bitwise_and(m: i32, n: i32) -> i32 {
        let mut result = n;
        for i in m..n {
            result &= i;
        }
        result
    }
}

2. Solution

impl Solution {
    pub fn range_bitwise_and(m: i32, n: i32) -> i32 {
        let mut n = n;
        while n > m {
            n &= n - 1;
        }
        n
    }
}

3. Solution

impl Solution {
    pub fn range_bitwise_and(m: i32, n: i32) -> i32 {
        if n > m {
            Self::range_bitwise_and(m >> 1, n >> 1) << 1
        } else {
            m
        }
    }
}

4. Solution

impl Solution {
    pub fn range_bitwise_and(m: i32, n: i32) -> i32 {
        let mut result = 0;
        let mut mask = 1 << 30;
        while mask != 0 && m & mask == n & mask {
            result |= m & mask;
            mask >>= 1;
        }
        result
    }
}