Solve climbing-stairs with python

Author: BEMELON

climbing-stairs/bemelon.py

@@ -0,0 +1,17 @@
+class Solution:
+    # Space complexity: O(1)
+    # Tiem complexity: O(n)
+    def climbStairs(self, n: int) -> int:
+        # dp[0] is n - 2
+        # dp[1] is n - 1
+        dp = [1, 2]
+
+        if n <= 2: 
+            return dp[n - 1]
+        
+        for i in range(3, n + 1): 
+            # dp[n] = dp[n - 1] + dp[n - 2]
+            #       = dp[1] + dp[0]
+            dp[(i - 1) % 2] = sum(dp)
+        
+        return dp[(n - 1) % 2]