Tree

The title alone is not a solvable specification, so begin by asking whether the tree is binary or n-ary, rooted or undirected, and whether the goal is traversal, height, validation, search, or a path property. Once the contract is known, choose a traversal deliberately. DFS is natural when a parent needs child results, for example height or subtree sums: return a value whose meaning is explicit for each node. BFS is natural for levels, nearest depth, or level-order output. Mark visited nodes if the input is an arbitrary graph rather than a guaranteed tree. Most traversals take O(n) time and O(h) recursion stack or O(w) queue space, where h is height and w maximum width. Mention null root, one node, a skewed tree, and duplicate values before coding.