如何按要求打印数组的排列情况？

数据结构与算法

问题描述：针对1，2，2，3，4，5这几个数字，要求打印出所有排列，但是4不能在第三位，3和5不能相连。
[TOC]

1.数组全排列dfs

 public void print(int[] nums) {
        int[] book = new int[nums.length];
        int[] result = new int[nums.length];
        int step = 0;
        dfs(nums, result, book, step);
    }
    public void dfs(int[] nums, int[] result, int[] book, int step) {
        if (step == book.length) {
            System.out.println("nums:" + Arrays.toString(result));
            return;
        }
        for (int i = 0; i < nums.length; i++) {
            if (book[i] == 0) {
                book[i] = 1;
                result[step] = nums[i];
                dfs(nums, result, book, step + 1);
                book[i] = 0;
            }
        }
    }

2.做手脚

肯定是把条件直接加在输出就可以了

public class Solution {
    public void print(int[] nums) {
        int[] book = new int[nums.length];
        int[] result = new int[nums.length];
        int step = 0;
        dfs(nums, result, book, step);
    }
    public void dfs(int[] nums, int[] result, int[] book, int step) {
        if (step == book.length) {
            boolean ok = true;
            if (result[2] == 4) {
                ok = false;
            }
            for (int i = 0; i < result.length - 1; i++) {
                if (result[i] == 3 && result[i + 1] == 5) {
                    ok = false;
                }
                if (result[i] == 5 && result[i + 1] == 3) {
                    ok = false;
                }
            }
            if (ok) {
                System.out.println("result:" + Arrays.toString(result));
            }
            return;
        }
        for (int i = 0; i < nums.length; i++) {
            if (book[i] == 0) {
                book[i] = 1;
                result[step] = nums[i];
                dfs(nums, result, book, step + 1);
                book[i] = 0;
            }
        }
    }
    public static void main(String[] args) {
        Solution solution = new Solution();
        int[] nums = {1, 2, 2, 3, 4, 5};
        solution.print(nums);
    }
}