[leetcode]Permutations @ Python
原题地址:https://oj.leetcode.com/problems/permutations/
题意:
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]
.
解题思路:穷举一个集合的全排列。这个就是python递归巧妙的使用了。
代码:
class Solution: # @param num, a list of integer # @return a list of lists of integers def permute(self, num): if len(num) == 0: return [] if len(num) == 1: return [num] res = [] for i in range(len(num)): for j in self.permute(num[:i] + num[i+1:]): res.append([num[i]] + j) return res