climbing stairs solution

Author: yoon-turtle

climbing-stairs/yoonthecoder.js

@@ -0,0 +1,17 @@
+function climbStairs(n) {
+  // if there's only 1 step, return 1
+  if (n === 1) return 1;
+  // initialize the first prev values (when n=1 and n=0 each)
+  let prev1 = 1;
+  let prev2 = 1;
+  // iterate through step 2 to n
+  for (let i = 2; i <= n; i++) {
+    let current = prev1 + prev2;
+    prev2 = prev1;
+    prev1 = current;
+  }
+  return prev1;
+}
+
+// Time complexity: O(n) - single for loop
+// Space Complexity: O(1)