Climbing Stairs

Author: casentino

climbing-stairs/casentino.ts

@@ -0,0 +1,17 @@
+function climbStairs(n: number): number {
+  const memo = new Array(n + 1).fill(-1);
+  function climb(stair: number) {
+    if (stair === 0) {
+      return 1;
+    }
+    if (stair < 0) {
+      return 0;
+    }
+    if (memo[stair] !== -1) {
+      return memo[stair];
+    }
+    memo[stair] = climb(stair - 1) + climb(stair - 2);
+    return memo[stair];
+  }
+  return climb(n);
+}