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f754c0d31f
* jump_search: doctest, docstring, type hint, inputs * jumpsearch.py: case number not found * trailing whitespace jump search
53 lines
1.4 KiB
Python
53 lines
1.4 KiB
Python
"""
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Pure Python implementation of the jump search algorithm.
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This algorithm iterates through a sorted collection with a step of n^(1/2),
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until the element compared is bigger than the one searched.
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It will then perform a linear search until it matches the wanted number.
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If not found, it returns -1.
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"""
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import math
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def jump_search(arr: list, x: int) -> int:
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"""
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Pure Python implementation of the jump search algorithm.
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Examples:
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>>> jump_search([0, 1, 2, 3, 4, 5], 3)
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3
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>>> jump_search([-5, -2, -1], -1)
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2
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>>> jump_search([0, 5, 10, 20], 8)
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-1
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>>> jump_search([0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610], 55)
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10
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"""
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n = len(arr)
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step = int(math.floor(math.sqrt(n)))
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prev = 0
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while arr[min(step, n) - 1] < x:
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prev = step
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step += int(math.floor(math.sqrt(n)))
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if prev >= n:
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return -1
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while arr[prev] < x:
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prev = prev + 1
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if prev == min(step, n):
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return -1
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if arr[prev] == x:
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return prev
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return -1
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if __name__ == "__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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x = int(input("Enter the number to be searched:\n"))
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res = jump_search(arr, x)
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if res == -1:
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print("Number not found!")
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else:
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print(f"Number {x} is at index {res}")
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