Add Tree Postorder Traversal in TypeScript

Tree_Postorder_Traversal/Tree_Postorder_Traversal.ts

@@ -0,0 +1,73 @@
+//Tree Postorder Traversal in TypeScript
+
+export {}
+
+// Tree Nodes 
+interface treeNodes
+{
+    val: number;
+    parent?: treeNodes;  
+    left?: treeNodes;   
+    right?: treeNodes;  
+}
+
+// Defining the nodes with their values and left right children. If a value is not given it is undefined.
+const node11: treeNodes = { val: 11 };
+const node10: treeNodes = { val: 10 };
+const node9: treeNodes = { val: 9 };
+const node8: treeNodes = { val: 8 };
+const node7: treeNodes = { val: 7 };
+const node6: treeNodes = { val: 6, left: node10, right: node11};
+const node5: treeNodes = { val: 5 };
+const node4: treeNodes = { val: 4, left: node8, right: node9 };
+const node3: treeNodes = { val: 3, left: node6, right: node7 };
+const node2: treeNodes = { val: 2, left: node4, right: node5 };
+const root:  treeNodes = { val: 1, left: node2, right: node3 };
+
+// Construct a tree by assigning parent
+function constructBinaryTree(): treeNodes
+{
+    root.parent = undefined;
+    node2.parent = root;
+    node3.parent = root;
+    node4.parent = node2;
+    node5.parent = node2;
+    node6.parent = node3;
+    node7.parent = node3;
+    node8.parent = node4;
+    node9.parent = node4;
+    node10.parent = node6;
+    node11.parent = node6;
+
+    return root;
+}
+
+// Recursive Function to call itself on left child, then on right child and then print value of current node 
+function postOrderTraversal(currentNode: treeNodes) 
+{
+    if (!currentNode)
+        return;
+    postOrderTraversal(currentNode.left); 
+    postOrderTraversal(currentNode.right);
+    console.log(currentNode.val + " -> ");
+}
+
+constructBinaryTree();
+console.log("The postorder traversal of the binary tree is :");
+postOrderTraversal(root);
+
+/*
+Output:
+The postorder traversal of the binary tree is :
+8 -> 
+9 -> 
+4 -> 
+5 -> 
+2 ->
+10 ->
+11 -> 
+6 -> 
+7 -> 
+3 -> 
+1 ->
+*/