2022-06-15

201. Bitwise AND of Numbers Range

Description

Given two integers left and right that represent the range [left, right], return the bitwise AND of all numbers in this range, inclusive.

Example 1:

Input: left = 5, right = 7
Output: 4

Example 2:

Input: left = 0, right = 0
Output: 0

Example 3:

Input: left = 1, right = 2147483647
Output: 0 

Constraints:

• 0 <= left <= right <= 2^31 - 1

Solution

Approach #0

func rangeBitwiseAnd(left int, right int) int {
    shift := 0
    for left < right {
        left, right = left>>1, right>>1
        shift++
    }
    return left << shift
}

Approach #1

func rangeBitwiseAnd(left int, right int) int {
    for left < right {
        right &= (right - 1)
    }
    return right
}