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psf/black code formatting (#1277)

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This commit is contained in:
William Zhang
2019-10-05 01:14:13 -04:00
committed by Christian Clauss
parent 07f04a2e55
commit 9eac17a408
291 changed files with 6014 additions and 4571 deletions
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34
backtracking/all_permutations.py
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@ -1,42 +1,42 @@
'''
"""
In this problem, we want to determine all possible permutations
of the given sequence. We use backtracking to solve this problem.
Time complexity: O(n! * n),
where n denotes the length of the given sequence.
'''
"""
def generate_all_permutations(sequence):
create_state_space_tree(sequence, [], 0, [0 for i in range(len(sequence))])
create_state_space_tree(sequence, [], 0, [0 for i in range(len(sequence))])
def create_state_space_tree(sequence, current_sequence, index, index_used):
'''
"""
Creates a state space tree to iterate through each branch using DFS.
We know that each state has exactly len(sequence) - index children.
It terminates when it reaches the end of the given sequence.
'''
"""
if index == len(sequence):
print(current_sequence)
return
if index == len(sequence):
print(current_sequence)
return
for i in range(len(sequence)):
if not index_used[i]:
current_sequence.append(sequence[i])
index_used[i] = True
create_state_space_tree(sequence, current_sequence, index + 1, index_used)
current_sequence.pop()
index_used[i] = False
for i in range(len(sequence)):
if not index_used[i]:
current_sequence.append(sequence[i])
index_used[i] = True
create_state_space_tree(sequence, current_sequence, index + 1, index_used)
current_sequence.pop()
index_used[i] = False
'''
"""
remove the comment to take an input from the user
print("Enter the elements")
sequence = list(map(int, input().split()))
'''
"""
sequence = [3, 1, 2, 4]
generate_all_permutations(sequence)