1. Binary Trees In computer science, a binary tree is a tree data structure in which each node has at most two children, which are referred to as the left child and the right child. struct node { int data; struct node* left; struct node* right; }

2. Tree Traversal Inorder Traversal Preorder Traversal Postorder Traversal Level order Traversal

3. Postorder Traversal Algorithm 1.Traverse the left subtree 2.Traverse the right subtree 3. Visit the root. void printPostorder (struct node* node) { if (node == NULL) return; // first recur on both subtrees printTree(node->left); printTree(node->right); // then deal with the node printf("%d ", node->data); }

4. Inorder Traversal Algorithm 1.Traverse the left subtree 2. Visit the root. 3. Traverse the right subtree void printPostorder (struct node* node) { if (node == NULL) return; printTree(node->left); printf("%d ", node->data); printTree(node->right); }

5. Preorder Traversal Algorithm 1. Visit the root. 2.Traverse the left subtree 3.Traverse the right subtree void printPostorder (struct node* node) { if (node == NULL) return; printf("%d ", node->data); printTree(node->left); printTree(node->right); }

6. Level order Traversal Level Order: 1, 2, 3, 4, 5 Use Queue

7. Binary Search Tree The common properties of binary search trees are as follows: 1. The left subtree of a node contains only nodes with keys less than the node's key. 2. The right subtree of a node contains only nodes with keys greater than the node's key. 3. The left and right subtree each must also be a binary search tree. 4. Each node can have up to two successor nodes. 5. There must be no duplicate nodes. 6. A unique path exists from the root to every other node.

8. Binary Search Tree