Create Climbing_Stairs.py

Python/Climbing_Stairs.py

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+def climb_stairs(number_of_steps: int) -> int:
+    """
+    LeetCdoe No.70: Climbing Stairs
+    Distinct ways to climb a number_of_steps staircase where each time you can either
+    climb 1 or 2 steps.
+
+    Args:
+        number_of_steps: number of steps on the staircase
+
+    Returns:
+        Distinct ways to climb a number_of_steps staircase
+
+    Raises:
+        AssertionError: number_of_steps not positive integer
+
+    >>> climb_stairs(3)
+    3
+    >>> climb_stairs(1)
+    1
+    >>> climb_stairs(-7)  # doctest: +ELLIPSIS
+    Traceback (most recent call last):
+        ...
+    AssertionError: number_of_steps needs to be positive integer, your input -7
+    """
+    assert (
+        isinstance(number_of_steps, int) and number_of_steps > 0
+    ), f"number_of_steps needs to be positive integer, your input {number_of_steps}"
+    if number_of_steps == 1:
+        return 1
+    previous, current = 1, 1
+    for _ in range(number_of_steps - 1):
+        current, previous = current + previous, current
+    return current