-
Notifications
You must be signed in to change notification settings - Fork 22
Expand file tree
/
Copy path46.permutations.py
More file actions
69 lines (56 loc) · 1.65 KB
/
46.permutations.py
File metadata and controls
69 lines (56 loc) · 1.65 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
# Tag: Array, Backtracking
# Time: O(N!)
# Space: O(N)
# Ref: -
# Note: -
# Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.
#
# Example 1:
# Input: nums = [1,2,3]
# Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
# Example 2:
# Input: nums = [0,1]
# Output: [[0,1],[1,0]]
# Example 3:
# Input: nums = [1]
# Output: [[1]]
#
#
# Constraints:
#
# 1 <= nums.length <= 6
# -10 <= nums[i] <= 10
# All the integers of nums are unique.
#
#
class Solution:
def permute(self, nums: List[int]) -> List[List[int]]:
res = []
self.dfs(nums, 0, res)
return res
def dfs(self, nums: List[int], level: int, answer: List[List[int]]):
if level == len(nums) - 1:
answer.append(nums.copy())
return
for i in range(level, len(nums)):
nums[i], nums[level] = nums[level], nums[i]
self.dfs(nums, level + 1, answer)
nums[i], nums[level] = nums[level], nums[i]
class Solution:
def permute(self, nums: List[int]) -> List[List[int]]:
res = []
visited = set()
tmp = []
self.dfs(nums, visited, tmp, res)
return res
def dfs(self, nums: List[int], visited: set, tmp: list[int], answer: List[List[int]]):
if len(tmp) == len(nums):
answer.append(tmp.copy())
return
for i in range(len(nums)):
if i not in visited:
visited.add(i)
tmp.append(nums[i])
self.dfs(nums, visited, tmp, answer)
tmp.pop()
visited.remove(i)