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47 lines
1021 B
47 lines
1021 B
from collections import deque
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from typing import List, Deque
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def merge(
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els1: List[int],
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els2: List[int],
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) -> List[int]:
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"""
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Merges two sorted lists into one, keeps order.
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>>> merge([1, 2, 3], [3, 4, 5])
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[1, 2, 3, 3, 4, 5]
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"""
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result = []
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i, j = 0, 0
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while i < len(els1) and j < len(els2):
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if els1[i] < els2[j]:
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result.append(els1[i])
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i += 1
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else:
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result.append(els2[j])
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j += 1
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result.extend(els1[i:])
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result.extend(els2[j:])
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return result
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def mergesort(elements: List[int]) -> List[int]:
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"""
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Sorts a given list.
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"""
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# -> if len(elements) == 0:
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# if not elements:
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if len(elements) <= 1:
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return elements
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buffer: Deque[List[int]] = deque()
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for el in elements:
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buffer.append([el])
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while len(buffer) > 1:
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h1: List[int] = buffer.popleft()
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h2: List[int] = buffer.popleft()
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buffer.append(merge(h1, h2))
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return buffer.pop()
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