Postorder traversal of Binary tree YASH PAL, 4 June 202028 June 2025 In postorder traversal of a binary tree, we first traverse the left subtree of the root node and then the right subtree of the root node, and then we traverse the root node of the binary tree.Properties of postorder traversingTraverse the left subtree of the root in postorderTraverse the right subtree of the root in postorderVisit the root node.let’s say we have a binary tree as you see in the image given below. to find the postorder of this tree we need to first divide the tree into the subtrees as you see in the image given below.and as we know that in postorder we need to visit the left subtree and the right subtree and then the root node of the tree. so the preorder of this tree is B C P but B is also a subtree so the postorder of B is D E Aso the postorder of the tree isD E A C Pnow the D is also a subtree so the postorder of D is T Q Sso the post order of the tree isT Q S E A C Pnow the E is also a subtree so the post order of E is D Eso the postorder of the tree isT Q S D E A C Pnow the C is also a subtree so the post order of C is F G Xso the postorder of the tree isT Q S D E A F G X Pbut the F is also a subtree so the postorder of F is Mso the postorder of the tree isT A S D E A M G X Pbut the G is also a subtree so the postorder of G is C Rso the postorder of the tree isT A S D E A M C R X PThis is the complete postorder of the binary tree.Program to find the postorder of binary tree using Python.from collections import deque class Node: def __init__(self, value): self.info = value self.lchild = None self.rchild = None class BinaryTree: def __init__(self): self.root = None def is_empty(self): return self.root is None def display(self): self._display(self.root, 0) print() def _display(self,p,level): if p is None: return self._display(p.rchild, level+1) print() for i in range(level): print(" ", end='') print(p.info) self._display(p.lchild, level+1) def preorder(self): self._preorder(self.root) print() def _preorder(self,p): if p is None: return print(p.info, " ", end='') self._preorder(p.lchild) self._preorder(p.rchild) def inorder(self): self._inorder(self.root) print() def _inorder(self,p): if p is None: return self._inorder(p.lchild) print(p.info," ", end='') self._inorder(p.rchild) def postorder(self): self._postorder(self.root) print() def _postorder(self,p): if p is None: return self._postorder(p.lchild) self._postorder(p.rchild) print(p.info," ",end='') def level_order(self): if self.root is None: print("Tree is empty") return qu = deque() qu.append(self.root) while len(qu) != 0: p = qu.popleft() print(p.info + " ", end='') if p.lchild is not None: qu.append(p.lchild) if p.rchild is not None: qu.append(p.rchild) def height(self): return self._height(self.root) def _height(self,p): if p is None: return 0 hL = self._height(p.lchild) hR = self._height(p.rchild) if hL > hR: return 1 + hL else: return 1 + hR def create_tree(self): self.root = Node('p') self.root.lchild = Node('Q') self.root.rchild = Node('R') self.root.lchild.lchild = Node('A') self.root.lchild.rchild = Node('B') self.root.rchild.lchild = Node('X') ########################## bt = BinaryTree() bt.create_tree() bt.display() print() print("Preorder : ") bt.preorder() print("") print("Inorder : ") bt.inorder() print() print("Postorder : ") bt.postorder() print() print("Level order : ") bt.level_order() print() print("Height of tree is ", bt.height()) Computer Science Tutorials Data Structures Tutorials computer scienceData Structure