Univalued Binary Tree - Solution & Explanation

The recursive DFS approach involves starting from the root and checking if every node has the same value as the root node. This can be achieved by recursively checking the left and right subtrees of each node. If a node value differs from the root node's value, we return false immediately.

The function isUnival() checks recursively whether the node value equals the desired value (root->val). This involves checking the left and right subtrees. If any node value doesn't match, it returns false.

An iterative BFS approach uses a queue to level-order traverse the tree. We compare each node's value to the root's value. If any node differs, the function returns false.

This C solution uses an explicit queue structure to iteratively traverse nodes level-wise, checking if each has the same value as the root. Queues ensure that nodes are processed in insertion order.