基数排序

基数排序并不需要直接对元素进行相互比较，也不需要将元素相互交换，需要做的就是对元素进行“分类”。根据关键字中各位的值，通过对排序的N个元素进行若干趟“分配”与“收集”来实现排序的。

• java

public class Ridex {
    public static void sort(int[] array) {
        int max = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] > max) {
                max = array[i];
            }
        }
        int time = 0;
        while (max > 0) {
            max /= 10;
            time++;
        }
        List<ArrayList> queue = new ArrayList<ArrayList>();
        for (int i = 0; i < 10; i++) {
            ArrayList<Integer> queue1 = new ArrayList<Integer>();
            queue.add(queue1);
        }
        for (int i = 0; i < time; i++) {
            for (int j = 0; j < array.length; j++) {
                int x = array[j] % (int) Math.pow(10, i + 1) / (int) Math.pow(10, i);
                ArrayList<Integer> queue2 = queue.get(x);
                queue2.add(array[j]);
                queue.set(x, queue2);
            }
            int count = 0;
            for (int k = 0; k < 10; k++) {
                while (queue.get(k).size() > 0) {
                    ArrayList<Integer> queue3 = queue.get(k);
                    array[count] = queue3.get(0);
                    queue3.remove(0);
                    count++;
                }
            }
        }
    }

    public static void show(int[] a) {
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
        System.out.println();
    }

    public static void main(String[] args) {
        int[] a = {80, 30, 11160, 40, 20, 10, 2250, 170};
        sort(a);
        show(a);
    }
}

• python

import math


class Radix:
    def radix_sort(self, data, radix=10):
        k = int(math.ceil(math.log(max(data), radix)))
        bucket = [[] for i in range(radix)]
        for i in range(1, k + 1):
            for j in data:
                bucket[j // (radix ** (i - 1)) % radix].append(j)
            del data[:]
            for z in bucket:
                data += z
                del z[:]
        return data


if __name__ == "__main__":
    s = [80, 30, 11160, 40, 20, 10, 2250, 170]
    radix = Radix()
    print(radix.radix_sort(s))