From 7758c2928816c7fc3fbee50de79e09b35aa38cff Mon Sep 17 00:00:00 2001
From: legitgoons <cksxkr5193@naver.com>
Date: Sat, 21 Dec 2024 10:37:02 +0900
Subject: [PATCH] Climbing Stairs

---
 legitgoons/Climbing Stairs.ts | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 legitgoons/Climbing Stairs.ts

diff --git a/legitgoons/Climbing Stairs.ts b/legitgoons/Climbing Stairs.ts
new file mode 100644
index 0000000..ad867c8
--- /dev/null
+++ b/legitgoons/Climbing Stairs.ts	
@@ -0,0 +1,26 @@
+/**
+ * 1칸 Or 2칸
+ * 45칸이면 일단 1+1+...+1
+ * n = 1 return 1
+ * n = 2 return 2
+ * n = 3 return 3
+ * n = 4 return 5 [1, 1, 1, 1] [2, 1, 1] [1, 2, 1] [1, 1, 2] [2, 2]
+ * n = 5 return 8 [1, 1, 1, 1, 1] [2, 1, 1, 1] [1, 2, 1, 1][1, 1, 2, 1][1, 1, 1, 2][2, 2, 1][2, 1, 2][1, 2, 2]
+ * 1, 2, 3, 5, 8 -> n = (n-2)번째 + (n-1)번째
+ * 새로운 함수 호출하니까 시간때문에 터짐 -> 걍 반복문 돌리자
+ */
+
+function climbStairs(n: number): number {
+  if (n <= 3) return n;
+
+  let x = 2;
+  let y = 3;
+  let sum = 0;
+
+  for (let i = 4; i <= n; i++) {
+    sum = x + y;
+    x = y;
+    y = sum;
+  }
+  return sum;
+}