Familystrokes - 338.

Proof. By definition a leaf has no children, thus rule 1 (vertical stroke) and rule 2 (horizontal stroke) are both inapplicable. ∎ Every internal node (node with childCnt ≥ 1 ) requires exactly one vertical stroke .

if childCnt > 0: // v has at least one child → internal internalCnt += 1 if childCnt >= 2: horizontalCnt += 1 338. FamilyStrokes

Memory – The adjacency list stores 2·(N‑1) integers, plus a stack/queue of at most N entries and a few counters: O(N) . 338. FamilyStrokes