add

climb_stairs.py

@@ -0,0 +1,14 @@
+def climbStairs(n: int) -> int:
+    if n < 1 or n > 45:
+        return 0
+    else:
+        a = 1
+        b = 1
+        for i in range(2, n + 1):
+            a, b = b, a + b
+        return b
+
+print(climbStairs(4))
+
+
+