LeetCode in Kotlin
3226. Number of Bit Changes to Make Two Integers Equal
Easy
You are given two positive integers n and k.
You can choose any bit in the binary representation of n that is equal to 1 and change it to 0.
Return the number of changes needed to make n equal to k. If it is impossible, return -1.
Example 1:
Input: n = 13, k = 4
Output: 2
Explanation:
Initially, the binary representations of n and k are n = (1101)2 and k = (0100)2.
We can change the first and fourth bits of n. The resulting integer is n = (**0**10**0**)2 = k.
Example 2:
Input: n = 21, k = 21
Output: 0
Explanation:
n and k are already equal, so no changes are needed.
Example 3:
Input: n = 14, k = 13
Output: -1
Explanation:
It is not possible to make n equal to k.
Constraints:
1 <= n, k <= 106
Solution
class Solution {
fun minChanges(n: Int, k: Int): Int {
var n = n
var k = k
if ((n or k) != n) {
return -1
}
var cnt = 0
while (n > 0 || k > 0) {
val bitN = n and 1
val bitK = k and 1
if (bitN == 1 && bitK == 0) {
cnt++
}
n = n shr 1
k = k shr 1
}
return cnt
}
}