pyFarmerGiles

# Move Farmer + Sheep + Corn + Wolf across river
# Programmed by Mike Kerry in December 2020
# Email:  [email protected]

def draw_image(bl, bb, br):
    print("Left | Boat  | Right")
    wl = bl.copy() + [" ", " ", " ", " "]
    wb = bb.copy() + [" ", " ", " ", " "]
    wr = br.copy() + [" ", " ", " ", " "]
    for x in range(4):
        print(wl[x] + "    |   " + wb[x] + "   |  " + wr[x])


def check_user(astr):
    # validate user string for any combo of C, F, S, W or comma or space, without duplicates
    # no other characters are allowed
    ret = []
    astr = astr.upper()
    for ch in astr:
        if ch in ret:
            return []        # duplicate item typed
        if ch in ["C", "F", "S", "W"]:
            ret.append(ch)
        elif ch != "," and ch != " ":
            return []
    if "F" not in ret:
        ret.append("F")         # Always include Farmer in the selection
    return ret


def check_present(ibank, sel):
    # check that the selection "sel" all exist on the specified bank
    for a in sel:
        if a not in ibank:
            return False
    return True


def check_remain(ibank, ires):
    # Check for a viable combination remaining when ires are removed from ibank
    obank = ibank.copy()    # make a local copy of the given bank

    # remove each item in "ires" from our copy of the bank
    for ch in ires:
        if ch in obank:
            obank.remove(ch)

    # check what's remaining for allowable combinations
    if "S" in obank:    # Sheep cannot be left alone with corn or wolf
        if "C" in obank or "W" in obank:
            return ["BAD"] + obank
    return obank


lbank = ["C", "F", "S", "W"]
rbank = []
boat = []
farmerbank = "L"        # Which bank Farmer is currently on

# Start Playing
moves = 0
while len(rbank) < 4:
    draw_image(lbank, boat, rbank)
    while True:
        userstr = input("Select items to move from " + farmerbank + " bank: ")
        user_selection = check_user(userstr)
        if not user_selection:
            print("Invalid selection, try again")
        break
    # user_selection contains a valid combo of C, F, S, W
    # check that all "user_selection" items exist on the current bank
    if farmerbank == "L":
        v = check_present(lbank, user_selection)
    else:
        v = check_present(rbank, user_selection)
    if not v:
        print("You selected items that are not on the current bank! FAIL!")
        break

    # check what will happen if selected items get moved
    if farmerbank == "L":
        v2 = check_remain(lbank, user_selection)
    else:
        v2 = check_remain(rbank, user_selection)

    if v2 and v2[0] == "BAD":
        print("You left an invalid combination on the", farmerbank, "bank")
        print(v2[1:])
        break

    # Move farmer to new bank
    if farmerbank == "L":
        lbank = v2
        farmerbank = "R"
    else:
        rbank = v2
        farmerbank = "L"

    # Put the farmer and the user selected items in the boat
    boat = user_selection
    draw_image(lbank, boat, rbank)

    input("Press Enter to arrive on " + farmerbank + " bank")

    # dump cargo on new bank
    if farmerbank == "L":
        lbank = lbank + boat
    else:
        rbank = rbank + boat
    boat = []
    moves += 1

print("You succeeded in", moves, "boat crossings")