LeetCode/cs/minimum-cost-to-hire-k-workers.cs

using System.Collections.Generic;

public class Solution {
    private struct Worker(int quality, int wage) {
        public int Quality => quality;
        public int Wage => wage;
        public double Ratio => (double)Wage / Quality;
    }
    private class WorkerComparator : IComparer<Worker> {
        public int Compare(Worker lhs, Worker rhs) {
            var l = lhs.Wage * rhs.Quality;
            var r = rhs.Wage * lhs.Quality;
            return l.CompareTo(r);
        }
    }

    public double MincostToHireWorkers(int[] quality, int[] wage, int k) {
        var workers = new List<Worker>(quality.Length);
        for (var i = 0; i < quality.Length; ++i) {
            workers.Add(new Worker(quality[i], wage[i]));
        }
        workers.Sort(new WorkerComparator());

        double cost = double.MaxValue;
        int currentQuality = 0;
        var heap = new PriorityQueue<int, int>();

        foreach (var worker in workers) {
            currentQuality += worker.Quality;
            heap.Enqueue(worker.Quality, -worker.Quality);

            if (heap.Count > k) {
                currentQuality -= heap.Dequeue();
            }

            if (heap.Count == k) {
                cost = Math.Min(cost, currentQuality * worker.Ratio);
            }
        }

        return cost;
    }
}