[week3] solve 70. Climbing Stairs

Author: bky373

climbing-stairs/bky373.java

@@ -0,0 +1,20 @@
+class Solution {
+
+    public int climbStairs(int n) {
+        int[] ans = new int[n + 1];
+        if (n <= 2) {
+            return n;
+        }
+        ans[1] = 1;
+        ans[2] = 2;
+
+        for (int i = 3; i < n + 1; i++) {
+            ans[i] = ans[i - 1] + ans[i - 2];
+        }
+        return ans[n];
+    }
+}
+/**
+ * TC: O(N)
+ * SC: O(N)
+ */