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* DRAFT: GitHub Actions: Test on Python 3.12 Repeats #8777 * #8777 Some of our dependencies will not be ready yet. * Python 3.12: Disable qiskit and tensorflow algorithms * updating DIRECTORY.md --------- Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
67 lines
1.9 KiB
Python
67 lines
1.9 KiB
Python
"""
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In the Combination Sum problem, we are given a list consisting of distinct integers.
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We need to find all the combinations whose sum equals to target given.
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We can use an element more than one.
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Time complexity(Average Case): O(n!)
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Constraints:
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1 <= candidates.length <= 30
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2 <= candidates[i] <= 40
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All elements of candidates are distinct.
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1 <= target <= 40
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"""
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def backtrack(
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candidates: list, path: list, answer: list, target: int, previous_index: int
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) -> None:
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"""
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A recursive function that searches for possible combinations. Backtracks in case
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of a bigger current combination value than the target value.
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Parameters
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----------
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previous_index: Last index from the previous search
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target: The value we need to obtain by summing our integers in the path list.
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answer: A list of possible combinations
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path: Current combination
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candidates: A list of integers we can use.
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"""
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if target == 0:
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answer.append(path.copy())
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else:
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for index in range(previous_index, len(candidates)):
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if target >= candidates[index]:
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path.append(candidates[index])
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backtrack(candidates, path, answer, target - candidates[index], index)
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path.pop(len(path) - 1)
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def combination_sum(candidates: list, target: int) -> list:
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"""
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>>> combination_sum([2, 3, 5], 8)
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[[2, 2, 2, 2], [2, 3, 3], [3, 5]]
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>>> combination_sum([2, 3, 6, 7], 7)
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[[2, 2, 3], [7]]
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>>> combination_sum([-8, 2.3, 0], 1)
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Traceback (most recent call last):
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...
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RecursionError: maximum recursion depth exceeded
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"""
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path = [] # type: list[int]
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answer = [] # type: list[int]
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backtrack(candidates, path, answer, target, 0)
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return answer
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def main() -> None:
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print(combination_sum([-8, 2.3, 0], 1))
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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main()
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