Day 23 - Bitwise AND of Numbers Range

Solution.kt

# https://leetcode.com/explore/featured/card/30-day-leetcoding-challenge/531/week-4/3308/

class Solution {
    fun rangeBitwiseAnd(m: Int, n: Int): Int {
        var mShifts = 0
        var nShifts = 0
        var M = m
        var N = n
        
        while (M > 0) {
            M = M shr 1
            mShifts += 1
        }
        
        while (N > 0) {
            N = N shr 1
            nShifts += 1
        }
        
        if (mShifts != nShifts) {
            return 0
        }
        
        var i = mShifts - 1
        var result = 0
        
        while (i >= 0) {
            val mask = 1 shl i
            
            if (m and mask == n and mask) {
                result += m and mask
            } else {
                break
            }
            i -= 1
        }
        
        return result
    }
}