1 answer published. Last candidate submission on Jun 6 2026, 9:35pm PDT. Interview question asked to Software Engineers interviewing at Flextronics, TuSimple, Instacart and other companies. Original question asked: Validate if a given tree is a valid binary search tree.. Question last reported by a candidate interviewing at Cisco for a Software Engineer interview on Jul 31 2026, 2:32pm PDT.