Python/searches/jump_search.py

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"""
Pure Python implementation of the jump search algorithm.
This algorithm iterates through a sorted collection with a step of n^(1/2),
until the element compared is bigger than the one searched.
It will then perform a linear search until it matches the wanted number.
If not found, it returns -1.
"""
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import math
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def jump_search(arr: list, x: int) -> int:
"""
Pure Python implementation of the jump search algorithm.
Examples:
>>> jump_search([0, 1, 2, 3, 4, 5], 3)
3
>>> jump_search([-5, -2, -1], -1)
2
>>> jump_search([0, 5, 10, 20], 8)
-1
>>> jump_search([0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610], 55)
10
"""
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n = len(arr)
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
step += int(math.floor(math.sqrt(n)))
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if prev >= n:
return -1
while arr[prev] < x:
prev = prev + 1
if prev == min(step, n):
return -1
if arr[prev] == x:
return prev
return -1
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
arr = [int(item) for item in user_input.split(",")]
x = int(input("Enter the number to be searched:\n"))
res = jump_search(arr, x)
if res == -1:
print("Number not found!")
else:
print(f"Number {x} is at index {res}")