(Java)LeetCode-46. Permutations

Given a collection of distinct 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],
[3,2,1]
]

这道题中规中矩吧，全排列没有重复的数组，就用递归即可。代码如下：
public List<List<Integer>> permute(int[] nums) {

boolean[] flags = new boolean[nums.length];
List<List<Integer>> result = new ArrayList<List<Integer>>();
List<Integer> empty = new ArrayList<Integer>();
permute(result,empty,nums,flags,0);
return result;
}

private void permute(List<List<Integer>> result,List<Integer> empty,int[] nums, boolean[] flags, int cnt) {
// TODO Auto-generated method stub

if(cnt == nums.length){
result.add(new ArrayList<Integer>(empty));
}
for(int i = 0; i < flags.length; i++){
if(flags[i] == false){
empty.add(nums[i]);
flags[i] = true;
permute(result, empty, nums, flags, cnt+1);
flags[i] = false;
empty.remove(empty.size()-1);
}
}
}

不过在网上看到一个类似的十分巧妙的想法，链接如下：http://blog.csdn.net/happyaaaaaaaaaaa/article/details/51534048 速度十分快