雇佣 K 位工人的总代价

/*
 * Problem: Given an array `costs`, hire `k` workers based on the following rules:
 * 1. In each round, hire one worker from the first `candidates` and the last `candidates` workers.
 * 2. Choose the worker with the minimum cost. If there's a tie, choose the worker with the smaller index.
 * 3. Return the total cost of hiring `k` workers.
 */
import java.util.*;
import java.util.stream.IntStream;

public class SolutionStream {
    public int totalCost(int[] costs, int k, int candidates) {
        int totalCost = 0;
        PriorityQueue<Integer> minHeap = new PriorityQueue<>((a, b) -> costs[a] == costs[b] ? a - b : costs[a] - costs[b]);
        for (int i = 0; i < candidates; i++) minHeap.offer(i);
        for (int i = costs.length - 1; i >= costs.length - candidates && i >= candidates; i--) minHeap.offer(i);
        Set<Integer> used = new HashSet<>();
        while (k > 0 && !minHeap.isEmpty()) {
            int idx = minHeap.poll();
            if (used.add(idx)) {
                totalCost += costs[idx];
                k--;
                if (idx >= candidates && idx < costs.length - candidates) {
                    if (idx - candidates >= 0) minHeap.offer(idx - candidates);
                    if (idx + candidates < costs.length) minHeap.offer(idx + candidates);
                }
            }
        }
        return totalCost;
    }
}