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64 lines
1.6 KiB
Python
64 lines
1.6 KiB
Python
"""
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Code contributed by Honey Sharma
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Source: https://en.wikipedia.org/wiki/Cycle_sort
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"""
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def cycle_sort(array: list) -> list:
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"""
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>>> cycle_sort([4, 3, 2, 1])
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[1, 2, 3, 4]
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>>> cycle_sort([-4, 20, 0, -50, 100, -1])
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[-50, -4, -1, 0, 20, 100]
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>>> cycle_sort([-.1, -.2, 1.3, -.8])
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[-0.8, -0.2, -0.1, 1.3]
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>>> cycle_sort([])
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[]
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"""
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ans = 0
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# Pass through the array to find cycles to rotate.
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for cycleStart in range(0, len(array) - 1):
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item = array[cycleStart]
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# finding the position for putting the item.
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pos = cycleStart
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for i in range(cycleStart + 1, len(array)):
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if array[i] < item:
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pos += 1
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# If the item is already present-not a cycle.
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if pos == cycleStart:
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continue
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# Otherwise, put the item there or right after any duplicates.
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while item == array[pos]:
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pos += 1
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array[pos], item = item, array[pos]
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ans += 1
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# Rotate the rest of the cycle.
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while pos != cycleStart:
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# Find where to put the item.
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pos = cycleStart
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for i in range(cycleStart + 1, len(array)):
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if array[i] < item:
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pos += 1
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# Put the item there or right after any duplicates.
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while item == array[pos]:
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pos += 1
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array[pos], item = item, array[pos]
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ans += 1
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return array
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if __name__ == "__main__":
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assert cycle_sort([4, 5, 3, 2, 1]) == [1, 2, 3, 4, 5]
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assert cycle_sort([0, 1, -10, 15, 2, -2]) == [-10, -2, 0, 1, 2, 15]
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