LeetCode in Kotlin
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
class Solution {
fun rangeBitwiseAnd(left: Int, right: Int): Int {
return if (left == right) left else right and MASKS[Integer.numberOfLeadingZeros(left xor right)]
}
companion object {
private val MASKS = intArrayOf(
0,
-0x80000000,
-0x40000000,
-0x20000000,
-0x10000000,
-0x8000000,
-0x4000000,
-0x2000000,
-0x1000000,
-0x800000,
-0x400000,
-0x200000,
-0x100000,
-0x80000,
-0x40000,
-0x20000,
-0x10000,
-0x8000,
-0x4000,
-0x2000,
-0x1000,
-0x800,
-0x400,
-0x200,
-0x100,
-0x80,
-0x40,
-0x20,
-0x10,
-0x8,
-0x4,
-0x2
)
}
}