From 626f44a031833e2a52bb71de19dbc7c38b6b5d89 Mon Sep 17 00:00:00 2001
From: Anukriti Banerjee <37472545+Anukriti167@users.noreply.github.com>
Date: Wed, 17 May 2023 10:46:39 +0530
Subject: [PATCH] Create 0145-binary-tree-postorder-traversal

Adding the Java solutions for the Postorder traversal
---
 java/0145-binary-tree-postorder-traversal | 46 +++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 java/0145-binary-tree-postorder-traversal

diff --git a/java/0145-binary-tree-postorder-traversal b/java/0145-binary-tree-postorder-traversal
new file mode 100644
index 000000000..e87a4d314
--- /dev/null
+++ b/java/0145-binary-tree-postorder-traversal
@@ -0,0 +1,46 @@
+class Solution {
+    // Iterative
+    public List<Integer> postorderTraversal(TreeNode root) {
+        Stack<TreeNode> stack = new Stack<>();
+        stack.add(root);
+        Stack<Boolean> visit = new Stack<>();
+        visit.add(false);
+
+        List<Integer> res = new ArrayList<>();
+
+        while(!stack.isEmpty()){
+            TreeNode curr=stack.pop();
+            boolean v = visit.pop();
+            if(curr != null){
+                if(v != false){
+                    res.add(curr.val);
+                }else{
+                    stack.add(curr);
+                    visit.add(true);
+                    stack.add(curr.right);
+                    visit.add(false);
+                    stack.add(curr.left);
+                    visit.add(false);
+                }
+            }
+        }
+        return res;
+    }
+}
+
+class Solution {
+    // Recursive
+    public void postorder(TreeNode root, List<Integer> res){
+        if(root == null) return;
+
+        postorder(root.left, res);
+        postorder(root.right, res);
+        res.add(root.val);
+    }
+    public List<Integer> postorderTraversal(TreeNode root) {
+        List<Integer> res = new ArrayList<>();
+
+        postorder(root, res);
+        return res;
+    }
+}