41 lines
1.4 KiB
Python
41 lines
1.4 KiB
Python
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"""Robust Quicksort implementation with variations"""
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import random
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def quicksort(arr, low=0, high=None, pivot_strategy='last'):
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if high is None:
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high = len(arr) - 1
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if low < high:
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# Choose pivot based on strategy
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if pivot_strategy == 'random':
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pivot_index = random.randint(low, high)
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arr[pivot_index], arr[high] = arr[high], arr[pivot_index]
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elif pivot_strategy == 'median-of-three':
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mid = (low + high) // 2
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# Find median of arr[low], arr[mid], arr[high]
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s = sorted([(arr[low], low), (arr[mid], mid), (arr[high], high)], key=lambda x: x[0])
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median_index = s[1][1]
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arr[median_index], arr[high] = arr[high], arr[median_index]
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# Partition
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p = partition(arr, low, high)
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# Recursively sort partitions
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quicksort(arr, low, p - 1, pivot_strategy)
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quicksort(arr, p + 1, high, pivot_strategy)
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def partition(arr, low, high):
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pivot = arr[high]
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i = low - 1
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for j in range(low, high):
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if arr[j] <= pivot:
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i += 1
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arr[i], arr[j] = arr[j], arr[i]
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arr[i + 1], arr[high] = arr[high], arr[i + 1]
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return i + 1
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# Example usage
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if __name__ == "__main__":
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data = [3, 6, 8, 10, 1, 2, 1, 5, 9, 4]
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print("Original data:", data)
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quicksort(data, pivot_strategy='median-of-three')
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print("Sorted data:", data)
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