java 全排列

排列组合，其实是试探双方，也称回溯算法
package com.test;

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        int[] a = { 1, 2, 3, 4,5,6 };
        test(a, 0);

    }

    private static void test(int[] a, int index) {
        if (index == a.length) {
            if(a[2]==4)return;
            else{
                for (int i = 0; i < a.length; i++) {
                     if(i!=a.length-1){
                         if((a[i]==5&&a[i+1]==3)||(a[i]==3&&a[i+1]==5))
                             return;
                         
                     }
                }
                
                for (int i = 0; i < a.length; i++) {
                    System.out.print(a[i] + " ");
                }
                System.out.println();
                return;
            }
            
        }
        for (int i = index; i < a.length; i++) {

            swap(a, index, i);
            test(a, index + 1);
            swap(a, i, index);
        }

    }

    private static void swap(int[] a, int i, int j) {
        int temp = a[i];
        a[i] = a[j];
        a[j] = temp;

    }

}