1 answer published. Last candidate submission on Jun 6 2026, 9:35pm PDT. Interview question asked to Software Engineers interviewing at WePay, InsideSales.Com, Guidewire Software 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 RingCentral for a Software Engineer interview on Aug 20 2026, 5:03am PDT.