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39 lines
1.2 KiB
Python
39 lines
1.2 KiB
Python
"""
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This is Booyer-Moore Majority Vote Algorithm. The problem statement goes like this:
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Given an integer array of size n, find all elements that appear more than ⌊ n/k ⌋ times.
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We have to solve in O(n) time and O(1) Space.
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URL : https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_majority_vote_algorithm
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"""
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from collections import Counter
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def majority_vote(votes: list[int], votes_needed_to_win: int) -> list[int]:
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"""
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>>> majority_vote([1, 2, 2, 3, 1, 3, 2], 3)
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[2]
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>>> majority_vote([1, 2, 2, 3, 1, 3, 2], 2)
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[]
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>>> majority_vote([1, 2, 2, 3, 1, 3, 2], 4)
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[1, 2, 3]
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"""
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majority_candidate_counter: Counter[int] = Counter()
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for vote in votes:
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majority_candidate_counter[vote] += 1
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if len(majority_candidate_counter) == votes_needed_to_win:
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majority_candidate_counter -= Counter(set(majority_candidate_counter))
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majority_candidate_counter = Counter(
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vote for vote in votes if vote in majority_candidate_counter
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)
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return [
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vote
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for vote in majority_candidate_counter
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if majority_candidate_counter[vote] > len(votes) / votes_needed_to_win
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]
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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