计数排序 CountingSort

计数排序的核心在于将输入的数据值转化为键存储在额外开辟的数组空间中。作为一种线性时间复杂度的排序，计数排序要求输入的数据必须是有确定范围的整数。

动画演示 :

案例代码 : (此代码有些瑕疵 , 不能处理负数)

    public static void main(String[] args) {
        //int[] arr = {10, 78, 65, 32, 21, 89, 13, 54, 7, 3};
        //sort(arr);
        int[] brr = {0, 1,1, 7, 8, 9, 10};
        //Tsort(brr, 3);
        CountingSort(brr);
    }

    public static void CountingSort(int[] arr) {
        int max = arr[0];
        for (int i = 1; i < arr.length; i++) {
            if (arr[i] > max)
                max = arr[i];
        }
        int[] count = new int[max + 1];
        for (int i = 0; i < arr.length; i++) {
            count[arr[i]]++;
        }

        //合并
        int n = 0;
        for (int i = 0; i < max; i++) {
            while (count[i] != 0) {
                arr[n++] = i;
                count[i]--;
            }
        }
        
        //打印
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }

 代码 :

    public static void CountingSorts(int[] arr) {
        int max = arr[0];
        int min = arr[0];
        for (int i = 1; i < arr.length; i++) {
            if (arr[i] > max)
                max = arr[i];
            else if (arr[i] < min)
                min = arr[i];
        }
        int[] count = new int[max - min + 1];
        for (int i = 0; i < arr.length; i++) {
            count[arr[i] - min]++;
        }

        //合并
        int n = 0;
        for (int i = 0; i < count.length; i++) {
            while (count[i] != 0) {
                arr[n++] = min + i;
                count[i]--;
            }
        }

        //打印
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }

这期就到这 .