46. Permutations
阿新 • • 發佈:2017-05-22
range == lock deep clas follow deepcopy list result
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] ]
題解
該題是求所有可能的排列組合,是一道典型的dfs類型的題
代碼(python實現)
import copy class Solution(object): def permute(self, nums):""" :type nums: List[int] :rtype: List[List[int]] """ if nums is None: return results = [] if len(nums) == 0: return results self.helper(nums, results, []) return results def helper(self, nums, results, list):if len(list) == len(nums): #註意此處是深度拷貝,如果用java語言寫則以list為輸入new出一個新的實例 results.append(copy.deepcopy(list)) return for i in range(len(nums)): if(nums[i] in list): continue list.append(nums[i]) self.helper(nums, results, list) list.pop()
46. Permutations