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Adding quick sort where random pivot point is chosen (TheAlgorithms#774)
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sorts/random_pivot_quick_sort.py

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"""
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Picks the random index as the pivot
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"""
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import random
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def partition(A, left_index, right_index):
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pivot = A[left_index]
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i = left_index + 1
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for j in range(left_index + 1, right_index):
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if A[j] < pivot:
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A[j], A[i] = A[i], A[j]
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i += 1
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A[left_index], A[i - 1] = A[i - 1], A[left_index]
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return i - 1
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def quick_sort_random(A, left, right):
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if left < right:
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pivot = random.randint(left, right - 1)
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A[pivot], A[left] = A[left], A[pivot] #switches the pivot with the left most bound
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pivot_index = partition(A, left, right)
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quick_sort_random(A, left, pivot_index) #recursive quicksort to the left of the pivot point
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quick_sort_random(A, pivot_index + 1, right) #recursive quicksort to the right of the pivot point
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def main():
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user_input = input('Enter numbers separated by a comma:\n').strip()
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arr = [int(item) for item in user_input.split(',')]
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quick_sort_random(arr, 0, len(arr))
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print(arr)
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if __name__ == "__main__":
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main()

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