LeetCode/java/total-cost-to-hire-k-workers.java

import java.util.Comparator;
import java.util.PriorityQueue;

class Solution {
  private record Worker(int cost, int queue) {}

  private static final Comparator<Worker> WORKER_CMP =
      Comparator.comparing(Worker::cost).thenComparing(Worker::queue);

  public long totalCost(int[] costs, int k, int candidates) {
    var q = new PriorityQueue<Worker>(WORKER_CMP);

    // Add left side
    for (int i = 0; i < candidates; ++i) {
      q.offer(new Worker(costs[i], 0));
    }

    // Add right side
    for (int i = Math.max(candidates, costs.length - candidates); i < costs.length; ++i) {
      q.offer(new Worker(costs[i], 1));
    }

    long cost = 0;

    int l = candidates, r = costs.length - 1 - candidates;
    for (int i = 0; i < k; ++i) {
      var worker = q.poll();
      cost += worker.cost();

      if (l <= r) {
        if (worker.queue() == 0) {
          q.offer(new Worker(costs[l], 0));
          ++l;
        } else {
          q.offer(new Worker(costs[r], 1));
          --r;
        }
      }
    }

    return cost;
  }
}