距离相等的条形码

/*
 * 思路：
 * 1. 统计每个条形码的出现频率。
 * 2. 将条形码按照出现频率从高到低排序。
 * 3. 使用流来简化频率统计和排序。
 */
import java.util.*;
import java.util.stream.Collectors;

public class SolutionStream {
    public int[] rearrangeBarcodes(int[] barcodes) {
        Map<Integer, Long> countMap = Arrays.stream(barcodes)
                .boxed()
                .collect(Collectors.groupingBy(e -> e, Collectors.counting()));

        PriorityQueue<Map.Entry<Integer, Long>> maxHeap = new PriorityQueue<>((a, b) -> Long.compare(b.getValue(), a.getValue()));
        maxHeap.addAll(countMap.entrySet());

        int[] result = new int[barcodes.length];
        int index = 0;
        while (!maxHeap.isEmpty()) {
            Map.Entry<Integer, Long> first = maxHeap.poll();
            if (index > 0 && result[index - 1] == first.getKey()) {
                Map.Entry<Integer, Long> second = maxHeap.poll();
                result[index++] = second.getKey();
                if (second.getValue() > 1) {
                    second.setValue(second.getValue() - 1);
                    maxHeap.add(second);
                }
                maxHeap.add(first);
            } else {
                result[index++] = first.getKey();
                if (first.getValue() > 1) {
                    first.setValue(first.getValue() - 1);
                    maxHeap.add(first);
                }
            }
        }

        return result;
    }
}