一些简单的算法

package com.zh.test;

public class Test7 {
    /**
     * @param args
     * 求全排列
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a[]={1,2,3,4};
        f(a, 0);
    }
    
    public static void f(int a[],int n){
        if(n == a.length -1){
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]);
            }
            System.out.println();
        }
        for(int i=n;i<a.length;i++){
            int t = a[i];
            a[i] = a[n];
            a[n] = t;
            
            f(a, n+1);
            
            t = a[n];
            a[n] = a[i];
            a[i] = t;
        }
    }

}