算法之洗牌算法

package com.math;

import java.util.Random;

/**
 * @author summer
 *
 */
public class Shuffle {

    static final int[] a = new int[54];
    static Random rnd = new Random(); 
    
    static{
        
        for(int i=1;i<55;i++)
            a[i-1] = i;
        
    }
    
    static void swap(int[] arr,int i,int j){
             int tmp = arr[i];
            arr[i] = arr[j];
            arr[j] = tmp;
    }
    
    public static void  shuffle(){
         for (int i=a.length; i>1; i--)
             swap(a, i-1, rnd.nextInt(i));
    }
    
    public static void main(String[]args){
        
        shuffle();
        for(int i:a){
            System.out.println(i);
        }
    }
}