3375. Minimum Operations to Make Array Values Equal to K

MediumView on LeetCode

Array Hash Table

Time: O(n)

Space: O(n)

Intuition

Minimum operations to make array values equal to k. All elements must be reducible to k.

Algorithm

1If any element < k: return -1. Count distinct values > k (each needs one operation).

Common Pitfalls

•Can only decrease values. If element < k: impossible. Each distinct value > k needs one op.

3375.cs

// Approach: Collect unique values > k; if any < k return -1; else count distinct unique values > k.
// Time: O(n) Space: O(n)

public class Solution
{
    public int MinOperations(int[] nums, int k)
    {
        HashSet<int> numsSet = new HashSet<int>(nums);
        int mn = nums.Min();
        if (mn < k)
            return -1;
        if (mn > k)
            return numsSet.Count;
        return numsSet.Count - 1;
    }
}

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