mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-10-16 18:51:14 +00:00
fceacf977f
* updating DIRECTORY.md
* types(permuations): Rename permute2
* Apply suggestions from code review
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
* fix(permutations): Call permute_recursive
* fix(permutations): Correct permutations order
---------
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
49 lines
1.3 KiB
Python
49 lines
1.3 KiB
Python
def permute_recursive(nums: list[int]) -> list[list[int]]:
|
|
"""
|
|
Return all permutations.
|
|
|
|
>>> permute_recursive([1, 2, 3])
|
|
[[3, 2, 1], [2, 3, 1], [1, 3, 2], [3, 1, 2], [2, 1, 3], [1, 2, 3]]
|
|
"""
|
|
result: list[list[int]] = []
|
|
if len(nums) == 0:
|
|
return [[]]
|
|
for _ in range(len(nums)):
|
|
n = nums.pop(0)
|
|
permutations = permute_recursive(nums)
|
|
for perm in permutations:
|
|
perm.append(n)
|
|
result.extend(permutations)
|
|
nums.append(n)
|
|
return result
|
|
|
|
|
|
def permute_backtrack(nums: list[int]) -> list[list[int]]:
|
|
"""
|
|
Return all permutations of the given list.
|
|
|
|
>>> permute_backtrack([1, 2, 3])
|
|
[[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 2, 1], [3, 1, 2]]
|
|
"""
|
|
|
|
def backtrack(start: int) -> None:
|
|
if start == len(nums) - 1:
|
|
output.append(nums[:])
|
|
else:
|
|
for i in range(start, len(nums)):
|
|
nums[start], nums[i] = nums[i], nums[start]
|
|
backtrack(start + 1)
|
|
nums[start], nums[i] = nums[i], nums[start] # backtrack
|
|
|
|
output: list[list[int]] = []
|
|
backtrack(0)
|
|
return output
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
res = permute_backtrack([1, 2, 3])
|
|
print(res)
|
|
doctest.testmod()
|