add solution for climbing-stairs

Author: Ujoonnee

climbing-stairs/Ujoonnee.java

@@ -0,0 +1,16 @@
+class Solution {
+    public int climbStairs(int n) {
+        if (n == 1) {
+            return 1;
+        }
+
+        int[] dp = new int[n+1];
+        dp[1] = 1;
+        dp[2] = 2;
+        for(int i = 3; i <= n; i++) {
+            dp[i] = dp[i-2] + dp[i-1];
+        }
+
+        return dp[n];
+    }
+}