day 17, norvig's solution

day 16, took norvig's solution

day 15, part 2

day 15, part 1

day 14, small refactoring

day 14, used faster algorithm

removed double linked list

renamings

day 15

day 14, part 2 with double linked list (does not work out, still to slow)

day 14, part 1

day 13

improved pruning for backtracking

day 12

day 11, use generator