Finished evaluate recursively

BST.java

@@ -91,6 +91,23 @@ public class BST {
     // This method takes a reference to the root of the expression, evaluates
     // the tree, and returns the result as an int.
     public int evaluate(BSTNode node) {
-        return -1; // replace this statement with your own return
+        String value = node.getInfo();
+        switch (value) {
+            case "+":
+                return evaluate(node.getLeft()) + evaluate(node.getRight());
+
+            case "-":
+                return evaluate(node.getLeft()) - evaluate(node.getRight());
+
+            case "*":
+                return evaluate(node.getLeft()) * evaluate(node.getRight());
+
+            case "/":
+                return evaluate(node.getLeft()) / evaluate(node.getRight());
+
+            default:
+                return Integer.parseInt(node.getInfo());
+        }
+
     }
 }