LC2997. Minimum Number of Operations to Make Array XOR Equal to K

Approach 1: Optimal

class Solution:
    def minOperations(self, nums: List[int], k: int) -> int:
        xor_all = 0
        for num in nums:
            xor_all ^= num
        
        return bin(xor_all ^ k).count('1')

Complexity

Time: $O(n)$
Space: $O(1)$

Notes

XOR is commutative and associative so order doesn’t matter. If we read the problem description a bit closely, the true goal is to turn the XOR(all elements) into $k$. And we just need to count the number of operations. So, we just need to compare this XOR(all elements) against $k$ and see which bits are not matching and that’s going to be the result.

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