Trees & Graphs

Intuit's trees-and-graphs round is a standard one. The problems sit in the easy-to-medium band, the shapes are the ones every list drills, and no signature trick is waiting to catch you. The bar is craftsmanship. What the round grades is whether the traversal you write is clean, handles the empty and single-node cases, and compiles and runs the first time. A hierarchy of accounts, a category tree, a grid of cells: each is a small graph underneath, and the same short walk solves most of them.

Almost everything in this family runs off one skeleton: a depth-first or breadth-first walk that remembers where it has been. A tree lets you drop the memory, because it has no cycles and every node has exactly one parent. A graph or a grid puts it back, since an edge can point in a circle and two paths can reach the same cell. Make that one distinction reflexive and the cluster mostly collapses into the same loop with different bookkeeping.

The Intuit angle

The algorithm is the smaller half of an Intuit tree question, so write it as production code, not as a race. Reports from the assessor and problem-solving rounds line up. The panel wants a fully compiling solution in Java, with edge cases handled. Often they want the same traversal twice, once recursively and once iteratively, because the follow-up to "find the height" is routinely "now do it without recursion." Clarify the shape of the input before you touch the keyboard, since the interviewers like to withhold a detail and watch whether you ask for it. Name the empty tree, the single node, and the null child out loud, then handle them. A correct, readable walk that clears its boundaries beats a clever one that trips on a missing child.