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* Simplify climbing stairs and use constant memory * number_of_steps Co-authored-by: Christian Clauss <cclauss@me.com>
43 lines
1.1 KiB
Python
43 lines
1.1 KiB
Python
#!/usr/bin/env python3
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def climb_stairs(number_of_steps: int) -> int:
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"""
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LeetCdoe No.70: Climbing Stairs
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Distinct ways to climb a number_of_steps staircase where each time you can either
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climb 1 or 2 steps.
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Args:
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number_of_steps: number of steps on the staircase
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Returns:
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Distinct ways to climb a number_of_steps staircase
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Raises:
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AssertionError: number_of_steps not positive integer
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>>> climb_stairs(3)
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3
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>>> climb_stairs(1)
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1
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>>> climb_stairs(-7) # doctest: +ELLIPSIS
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Traceback (most recent call last):
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...
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AssertionError: number_of_steps needs to be positive integer, your input -7
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"""
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assert (
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isinstance(number_of_steps, int) and number_of_steps > 0
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), f"number_of_steps needs to be positive integer, your input {number_of_steps}"
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if number_of_steps == 1:
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return 1
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previous, current = 1, 1
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for _ in range(number_of_steps - 1):
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current, previous = current + previous, current
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return current
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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