基数排序

 

 

/**
 * 基数排序
 * 
 * @author lp
 *
 */
public class RadixSort {
    
    public static void radixSort(int[] array) {
        // 首先确定排序的趟数;
        int max = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] > max) {
                max = array[i];
            }
        }
        
        int time = 0;
        // 判断位数;
        while (max > 0) {
            max /= 10;
            time++;
        }

        // 建立10个队列;
        List<ArrayList> queue = new ArrayList<ArrayList>();
        for (int i = 0; i < 10; i++) {
            ArrayList<Integer> queue1 = new ArrayList<Integer>();
            queue.add(queue1);
        }

        // 进行time次分配和收集;
        for (int i = 0; i < time; i++) {
            // 分配数组元素;
            for (int j = 0; j < array.length; j++) {
                // 得到数字的第time+1位数;
                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;// 元素计数器;
            // 收集队列元素;
            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 main(String[] args) {
        int array[] = { 49, 38, 65, 97, 76, 13, 27, 49, 78, 34, 12, 64, 5, 4, 62, 99, 98, 54, 101, 56, 17, 18, 23, 34, 15,35, 25, 53, 51 };
        
        radixSort(array);
        
        for (int element : array) {
            System.out.print(element + " ");
        }
    }

}