LeetCode 46. 全排列

给定一个没有重复数字的序列，返回其所有可能的全排列。

示例:

输入: [1,2,3]
输出:
[
[1,2,3],
[1,3,2],
[2,1,3],
[2,3,1],
[3,1,2],
[3,2,1]
]

class Solution(object):
    def permute(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        res = []
        self.dfs(nums, [], res)
        return res

    def dfs(self, nums, path, res):
        if not nums:
            res.append(path)
        for i in xrange(len(nums)):
            self.dfs(nums[:i]+nums[i+1:], path+[nums[i]], res)