Binary Trees – Basic Operations

A binary tree node has at most two children: left and right. A common use is a binary search tree (BST) where left < node < right, enabling O(log n) lookup on average.

struct TreeNode {
    int key;
    struct TreeNode *left;
    struct TreeNode *right;
};

Key functions:

• insert(root, key) – recursively finds the position.
• search(root, key) – returns node or NULL.
• inorder(root) – visits nodes in sorted order.

Balancing (AVL, Red‑Black) is covered later.