Traversing in a Binary Tree YASH PAL, 3 June 202028 May 2024 Traversing a binary tree means visiting each node of the tree exactly once. and as we know the nodes of the tree are arranged in a hierarchical order so there are different ways to traverse a binary tree. we have three main tasks to traverse in the tree. visiting the root node. visiting the left subtree. visiting the right subtree. Types of traversing in a binary tree. Preorder Postorder In order Level order Preorder Traversing In preorder traversing first, wevisit the root node.then we traverse the left subtree of the root node in preorderthen we traverse the right subtree of the root node in preorder In order Traversing In inorder traversing first, weTraverse the left subtree of the root node in inorderthen we visit the root nodethen we traverse the right subtree of the root in order Postorder traversing In postorder traversing first, weTraverse the left subtree of the root node in postorderTraverse the right subtree of the root node in postordervisit the root node. Level order Traversing In level order traversing nodes are traversed level by level. so we have a binary tree as you see in the given below image. so the Preorder traversing is – P A S T Q E D X M R C Postorder traversing – T Q S D E A M C R X P In order traversing – T S Q A E D P M X C R Level order traversing – P A X T Z M G Y L F C Program to implement traversing in the 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