LeetCode/cs/minimum-operations-to-make-array-values-equal-to-k.cs

public class Solution {
    public int MinOperations(int[] nums, int k) {
        var toUse = new HashSet<int>();
        foreach (var x in nums) {
            if (x < k) {
                // can't use any number of operations
                return -1;
            } else if (x > k) {
                // gotta use it at least once
                toUse.Add(x);
            }
        }

        return toUse.Count;
    }
}