Java排序算法之桶排序详解

public static void main(String[] args) {
    double[] arr = new double[]{4.12, 6.421, 0.0023, 3.0, 2.123, 8.122, 4.12, 10.09};
    bucketSort(arr);
    for (double v : arr) {
        System.out.println(v);
    }


}


public static void bucketSort(double[] arr) {
    //1.取出数组中的最大值和最小值
    double max = Double.MIN_VALUE;
    double min = Double.MAX_VALUE;
    for (int i = 0; i < arr.length - 1; i++) {
        if (arr[i] < min) {
            min = arr[i];
        }
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    //2.初始化桶
    //桶的数量
    int bucketNum = arr.length;
    //每个桶的区间跨度
    double span = (max - min + 1) / bucketNum;
    ArrayList<LinkedList<Double>> bucketList = new ArrayList<LinkedList<Double>>(bucketNum);
    //在桶列表中添加元素个数的空桶
    for (int i = 0; i < bucketNum; i++) {
        bucketList.add(new LinkedList<Double>());
    }
    //3.遍历原始数组，将每个元素放入桶中
    for (int i = 0; i < arr.length; i++) {
        //获取桶的下标
        int num = (int) Math.floor((arr[i] - min) / span);//这里计算的结果是第几个桶，用Math.floor取到桶的下标，比如计算结果是2.5，说明应该放到第三个桶中，下标为2
        bucketList.get(num).add(arr[i]);
    }
    //4.对桶内元素进行排序
    for (int i = 0; i < bucketList.size(); i++) {
        Collections.sort(bucketList.get(i));
    }
    //5.输出全部元素
    double[] sortArray = new double[arr.length];
    int index = 0;
    for (LinkedList<Double> list : bucketList) {
        for (Double aDouble : list) {
            sortArray[index] = aDouble;
            index++;
        }
    }
}