Partial Solutions to VerifyThis 2016 Challenges 2 and 3 with VeriFast

We describe our partial solutions, using our VeriFast separation-logic based tool for modular formal verification of C and Java programs, to Challenges 2 and 3 of the VerifyThis 2016 Verification Competition, involving the verification of crash-freedom and certain correctness properties of code fragments implementing constant-space tree traversal and a tree barrier.