mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-27 17:56:29 +08:00
1c0f350ad6
* Add the intial translation of code of all the languages * test * revert * Remove * Add Python and Java code for EN version
46 lines
1.4 KiB
Python
46 lines
1.4 KiB
Python
"""
|
|
File: permutations_ii.py
|
|
Created Time: 2023-04-15
|
|
Author: krahets (krahets@163.com)
|
|
"""
|
|
|
|
|
|
def backtrack(
|
|
state: list[int], choices: list[int], selected: list[bool], res: list[list[int]]
|
|
):
|
|
"""Backtracking algorithm: Permutation II"""
|
|
# When the state length equals the number of elements, record the solution
|
|
if len(state) == len(choices):
|
|
res.append(list(state))
|
|
return
|
|
# Traverse all choices
|
|
duplicated = set[int]()
|
|
for i, choice in enumerate(choices):
|
|
# Pruning: do not allow repeated selection of elements and do not allow repeated selection of equal elements
|
|
if not selected[i] and choice not in duplicated:
|
|
# Attempt: make a choice, update the state
|
|
duplicated.add(choice) # Record selected element values
|
|
selected[i] = True
|
|
state.append(choice)
|
|
# Proceed to the next round of selection
|
|
backtrack(state, choices, selected, res)
|
|
# Retract: undo the choice, restore to the previous state
|
|
selected[i] = False
|
|
state.pop()
|
|
|
|
|
|
def permutations_ii(nums: list[int]) -> list[list[int]]:
|
|
"""Permutation II"""
|
|
res = []
|
|
backtrack(state=[], choices=nums, selected=[False] * len(nums), res=res)
|
|
return res
|
|
|
|
|
|
"""Driver Code"""
|
|
if __name__ == "__main__":
|
|
nums = [1, 2, 2]
|
|
|
|
res = permutations_ii(nums)
|
|
|
|
print(f"Input array nums = {nums}")
|
|
print(f"All permutations res = {res}")
|