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44 lines
1.0 KiB
Python
44 lines
1.0 KiB
Python
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"""
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A triangular number or triangle number counts objects arranged in an
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equilateral triangle. This module provides a function to generate n'th
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triangular number.
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For more information about triangular numbers, refer to:
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https://en.wikipedia.org/wiki/Triangular_number
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"""
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def triangular_number(position: int) -> int:
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"""
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Generate the triangular number at the specified position.
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Args:
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position (int): The position of the triangular number to generate.
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Returns:
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int: The triangular number at the specified position.
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Raises:
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ValueError: If `position` is negative.
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Examples:
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>>> triangular_number(1)
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1
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>>> triangular_number(3)
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6
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>>> triangular_number(-1)
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Traceback (most recent call last):
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...
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ValueError: param `position` must be non-negative
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"""
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if position < 0:
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raise ValueError("param `position` must be non-negative")
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return position * (position + 1) // 2
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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