Exponential time and implicit graphs

Problems

Name Solved / Tries Average tries Average tries to solve
A Knights in Fen 30/236 (13%) 7.87 7.87
B Bag of Tiles 28/179 (16%) 5.97 4.93
C Bracket Pairing 2/17 (12%) 4.25 1.00
D Basin City Surveillance 2/23 (9%) 3.83 4.00