Lowest Common Ancestor (LCA):

• The LCA of two nodes is the deepest node that is an ancestor of both.
• Binary lifting can be used to efficiently compute LCA.

Diameter of a Tree:

• The longest path between any two nodes in a tree.
• Solved by performing two BFS or DFS:
  1. Find the farthest node from any node.
  2. From that node, find the farthest node again, which gives the diameter.

Binary Search Tree (BST) Operations:

• Insertion, Deletion, and Search:

struct Node {
    int key;
    Node *left, *right;

    Node(int k) : key(k), left(NULL), right(NULL) {}
};

Node* insert(Node* root, int key) {
    if (!root) return new Node(key);

    if (key < root->key)
        root->left = insert(root->left, key);
    else if (key > root->key)
        root->right = insert(root->right, key);

    return root;
}