[SAM] Week 2 solutions

climbing-stairs/samthekorean.py

@@ -1,3 +1,24 @@
+# TC: O(n) — the loop runs n-2 times in the worst case
+# SC: O(1) — only a constant number of variables are used (a, b, c)
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if n == 1 :
+            return 1
+        if n == 2 :
+            return 2
+
+        a = 1
+        b = 2
+
+        for i in range(n - 2) :
+            c = a + b
+            a = b
+            b = c
+
+        return b 
+
+
+# 이전 풀이
 # Time complexity : O(n)
 # Space complexity : O(1)
 class Solution:
@@ -16,3 +37,4 @@ def climbStairs(self, n: int) -> int:
             a, b = b, result
 
         return result
+