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3226. Number of Bit Changes to Make Two Integers Equal 👍

  • Time: $O(1)$
  • Space: $O(1)$
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class Solution {
 public:
  int minChanges(unsigned n, unsigned k) {
    // n needs to be a superset of k.
    return (n & k) == k ? popcount(n ^ k) : -1;
  }
};

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class Solution {
  public int minChanges(int n, int k) {
    // n needs to be a superset of k.
    return (n & k) == k ? Integer.bitCount(n ^ k) : -1;
  }
}

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class Solution:
  def minChanges(self, n: int, k: int) -> int:
    # n needs to be a superset of k.
    return (n ^ k).bit_count() if (n & k) == k else -1