leetcode--Permutations

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

[java] view plain copy

1. public class Solution {  
2.     public List<List<Integer>> permute(int[] nums) {  
3.         List<List<Integer>> res = new ArrayList<List<Integer>>();  
4.         solve(nums, 0, res);  
5.         return res;  
6.     }  
7.       
8.     public void solve(int[] nums,int i,List<List<Integer>> res){  
9.         if(i==nums.length-1){  
10.             List<Integer> t = new ArrayList<Integer>();  
11.             for(int j=0;j<nums.length;j++){  
12.                 t.add(nums[j]);  
13.             }             
14.             res.add(t);  
15.         }  
16.         for(int j=i;j<nums.length;j++){  
17.             int t = nums[i];  
18.             nums[i] = nums[j];  
19.             nums[j] = t;  
20.             solve(nums, i+1, res);  
21.             t = nums[i];  
22.             nums[i] = nums[j];  
23.             nums[j] = t;  
24.         }  
25.     }  
26. }  

原文链接http://blog.csdn.net/crazy__chen/article/details/46388851