LeetCode in TypeScript
201. Bitwise AND of Numbers Range
Medium
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 <= 231 - 1
Solution
function rangeBitwiseAnd(left: number, right: number): number {
const MASKS: number[] = [
0x00000000, 0x80000000, 0xc0000000, 0xe0000000, 0xf0000000, 0xf8000000, 0xfc000000, 0xfe000000, 0xff000000,
0xff800000, 0xffc00000, 0xffe00000, 0xfff00000, 0xfff80000, 0xfffc0000, 0xfffe0000, 0xffff0000, 0xffff8000,
0xffffc000, 0xffffe000, 0xfffff000, 0xfffff800, 0xfffffc00, 0xfffffe00, 0xffffff00, 0xffffff80, 0xffffffc0,
0xffffffe0, 0xfffffff0, 0xfffffff8, 0xfffffffc, 0xfffffffe,
]
if (left === right) {
return left
}
const leadingZeros = Math.clz32(left ^ right)
return right & MASKS[leadingZeros]
}
export { rangeBitwiseAnd }