[LeetCode]题解（python）：046-Permutations

---

题目来源

---

https://leetcode.com/problems/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], and [3,2,1].

---

题意分析

---

Input: a list 

Output: a permutations

Conditions:全排列

---

题目思路

---

递归解决。注意到python取list的若干位很方便，分片~然后仔细发现不单是全排序，而且还是字典序（因为每一次遍历都是从小到大的，遍历顺序取决~）

---

AC代码（Python）

---

class Solution(object):
    def permute(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        if len(nums) == 1:
            return [nums]
        res = []
        for i in range(len(nums)):
            for j in self.permute(nums[:i] + nums[i+1:]):
                res.append([nums[i]] + j)
        return res