add climbing-stairs solution

Author: nakjun12

climbing-stairs/nakjun12.ts

@@ -0,0 +1,10 @@
+// T.C: O(n)
+// S.C: O(n)
+
+function climbStairs(n: number) {
+  const dp = { 1: 1, 2: 2 };
+  for (let i = 3; i <= n; i++) {
+    dp[i] = dp[i - 1] + dp[i - 2];
+  }
+  return dp[n];
+}