binary tree post order traversal

fishercoder1534 · fishercoder1534 · commit 7a276632051c · 2016-08-24T07:51:48.000-07:00
diff --git a/HARD/src/hard/BinaryTreePostOrderTraversal.java b/HARD/src/hard/BinaryTreePostOrderTraversal.java
@@ -0,0 +1,23 @@
+package hard;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import classes.TreeNode;
+
+public class BinaryTreePostOrderTraversal {
+
+    public List<Integer> postorderTraversal(TreeNode root) {
+        List<Integer> list = new ArrayList();
+        return post(root, list);
+    }
+    
+    List<Integer> post(TreeNode root, List<Integer> list){
+        if(root == null) return list;
+        if(root.left != null) post(root.left, list);
+        if(root.right != null) post(root.right, list);
+        list.add(root.val);
+        return list;
+    }
+
+}
