tictactoe.gno

 1package tictactoe
 2
 3import "strconv"
 4
 5var (
 6	board  [9]string
 7	turn   = "X"
 8	winner string
 9	moves  int
10)
11
12func init() {
13	for i := 0; i < 9; i++ {
14		board[i] = "."
15	}
16}
17
18// Mark places the current player's token at pos (0=top-left ... 8=bottom-right, row-major).
19func Mark(pos int) string {
20	if winner != "" {
21		return "game over: " + winner
22	}
23	if pos < 0 || pos > 8 {
24		return "invalid position: use 0-8"
25	}
26	if board[pos] != "." {
27		return "cell already taken"
28	}
29	board[pos] = turn
30	moves++
31	if checkWin() {
32		winner = turn
33		return turn + " wins!"
34	}
35	if moves == 9 {
36		winner = "draw"
37		return "draw!"
38	}
39	if turn == "X" {
40		turn = "O"
41	} else {
42		turn = "X"
43	}
44	return "ok"
45}
46
47func checkWin() bool {
48	lines := [8][3]int{
49		{0, 1, 2}, {3, 4, 5}, {6, 7, 8},
50		{0, 3, 6}, {1, 4, 7}, {2, 5, 8},
51		{0, 4, 8}, {2, 4, 6},
52	}
53	for _, l := range lines {
54		if board[l[0]] != "." && board[l[0]] == board[l[1]] && board[l[1]] == board[l[2]] {
55			return true
56		}
57	}
58	return false
59}
60
61func Render(_ string) string {
62	out := "# Tic-Tac-Toe\n\n"
63	out += "```\n"
64	out += " " + board[0] + " | " + board[1] + " | " + board[2] + "\n"
65	out += "---+---+---\n"
66	out += " " + board[3] + " | " + board[4] + " | " + board[5] + "\n"
67	out += "---+---+---\n"
68	out += " " + board[6] + " | " + board[7] + " | " + board[8] + "\n"
69	out += "```\n\n"
70	if winner == "draw" {
71		out += "**Draw!**\n"
72	} else if winner != "" {
73		out += "**" + winner + " wins!**\n"
74	} else {
75		out += "Next turn: **" + turn + "**\n\n"
76		out += "Positions: 0=top-left, 4=center, 8=bottom-right (row-major)\n"
77	}
78	out += "\nMoves played: " + strconv.Itoa(moves) + "\n"
79	return out
80}