Method longer_path

src/agents/graph.py:87–132

Build a path slightly longer than the shortest path.

(self, dst: Pos, snake: Snake)

        return []

    def longer_path(self, dst: Pos, snake: Snake) -> list[Direction]:
        """Build a path slightly longer than the shortest path."""
        shortest = self.shortest_path(dst, snake)
        longest: list[Direction] = []
        cur = snake.head()

        for direc in shortest:
            nxt = cur.adj(direc)
            extended = False

            test_direcs = []
            if direc in (Direction.UP, Direction.DOWN):
                test_direcs = [Direction.LEFT, Direction.RIGHT]
            else:
                test_direcs = [Direction.UP, Direction.DOWN]

            for test_direc in test_direcs:
                cur_extended = cur.adj(test_direc)
                nxt_extended = nxt.adj(test_direc)

                cur_extendable = (
                    self.is_reachable(cur_extended, snake)
                    # eating the food might trap the snake, so we don't extend if there's food
                    and not snake.is_food(cur_extended)
                )

                nxt_extendable = (
                    self.is_reachable(nxt_extended, snake)
                    # coords[1] is the second last snake body which will become
                    # the new tail after the move, so it's safe to extend
                    or nxt_extended == snake.coords[1]
                )

                if cur_extendable and nxt_extendable:
                    longest.append(test_direc)
                    longest.append(direc)
                    longest.append(test_direc.opposite())
                    extended = True
                    break

            if not extended:
                longest.append(direc)

            cur = nxt

        return longest

    def build_hamilton_index(self, path: list[Direction], snake: Snake) -> None:
        self.hamilton_index = [list(row) for row in snake.grid]