Added Climbing Stairs solution (LeetCode #70)

Author: noorinrahila

dynamic_programming/climbing_stairs.py

@@ -1,42 +1,26 @@
-#!/usr/bin/env python3
-
-
-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
-
-
+"""
+Climbing Stairs Problem
+LeetCode #70
+Author: Noorin Rahila
+"""
+
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        a = 1
+        b = 1
+        if n == 0:
+            return 0
+        elif n == 1:
+            return 1
+        else:
+            for i in range(1, n):
+                c = a + b
+                a = b
+                b = c
+            return b
+
+# Example usage
 if __name__ == "__main__":
-    import doctest
+    s = Solution()
+    print(s.climbStairs(5))  # Output: 8
 
-    doctest.testmod()