#
# Uses a depth-first search to find a path from a randomly-generated point to
# the "treasure" at (0, 1) on a 4x4 coordinate plane:
#
#     0 1 2 3
#   0 - - - -
#   1 * - - -
#   2 - - - -
#   3 - - - -
#

class Coordinates
    attr_accessor :x
    attr_accessor :y

    def print
        puts "(#{@x}, #{@y})"
    end

    def is_on_treasure?
        @x == 0 and @y == 1
    end
end

coordinates = Coordinates.new

srand # reset the random seed
coordinates.x = rand 4

srand # reset the random seed
coordinates.y = rand 4

visited = []
to_visit = []

while not coordinates.is_on_treasure?
    visited.append coordinates.dup

    if coordinates.x < 3
        right = coordinates.dup
        right.x += 1
        to_visit.append right
    end

    if coordinates.y < 3
        down = coordinates.dup
        down.y += 1
        to_visit.append down
    end

    if coordinates.x > 0
        left = coordinates.dup
        left.x -= 1
        to_visit.append left
    end

    if coordinates.y > 0
        up = coordinates.dup
        up.y -= 1
        to_visit.append up
    end

    coordinates = to_visit.last
end

visited.append coordinates

puts "path: "
visited.each do |c|
    print "- "
    c.print
end