11Java基数排序

Posted 2021-05-01 菜鸟学编程

Java基数排序

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package sort;

import java.util.Arrays;

class RadixSort {


    private static int getMax(int arr[], int n) {
        int mx = arr[0];
        for (int i = 1; i < n; i++)
            if (arr[i] > mx)
                mx = arr[i];
        return mx;
    }

    private static void countSort(int arr[], int n, int exp)
    {
        int output[] = new int[n];
        int i;
        int count[] = new int[10];
        Arrays.fill(count,0);

        for (i = 0; i < n; i++)
            count[ (arr[i]/exp)%10 ]++;

        for (i = 1; i < 10; i++)
            count[i] += count[i - 1];

        for (i = n - 1; i >= 0; i--)
        {
            output[count[ (arr[i]/exp)%10 ] - 1] = arr[i];
            count[ (arr[i]/exp)%10 ]--;
        }

        for (i = 0; i < n; i++)
            arr[i] = output[i];
    }

    private static void radixsort(int arr[], int n) {

        int m = getMax(arr, n);


        for (int exp = 1; m/exp > 0; exp *= 10)
            countSort(arr, n, exp);
    }


    static void print(int arr[], int n)
    {
        for (int i=0; i<n; i++)
            System.out.print(arr[i]+" ");
    }



    public static void main (String[] args)
    {
        int arr[] = {170, 45, 75, 90, 802, 24, 2, 66};
        int n = arr.length;
        radixsort(arr, n);
        print(arr, n);
    }
}
// Written by James Mc Dermott(theycallmemac)