Add a Lua script for a simple Tic-Tac-Toe game

This script implements a human vs. computer Tic-Tac-Toe game with functionalities like move validation, win-checking, and a replay option. It includes a basic AI for the computer's moves and displays the game board dynamically. This is an "extra" script that will be omitted from the 160k disk image.

Author: Lethja

demo/extra/xo.lua

@@ -0,0 +1,158 @@
+#!/usr/bin/env lua
+
+local function printBoard(board)
+	io.write("\n---------\n")
+	for i = 1, 9 do
+		io.write(board[i] .. (i % 3 ~= 0 and " | " or "\n---------\n"))
+	end
+	print()
+end
+
+local function checkWin(board, player)
+	if (board[5] == player) and ((board[1] == player and board[9] == player) or (board[3] == player and board[7] == player)) then
+		return true
+	end
+
+	for i = 1, 7, 3 do
+		if board[i] == player and board[i + 1] == player and board[i + 2] == player then
+			return true
+		end
+	end
+
+	for i = 1, 3 do
+		if board[i] == player and board[i + 3] == player and board[i + 6] == player then
+			return true
+		end
+	end
+
+	return false
+end
+
+local function boardFull(board)
+	for i = 1, 9 do
+		if tonumber(board[i]) then
+			return false
+		end
+	end
+	return true
+end
+
+local function humanMove(board)
+	while true do
+		io.write("Enter a number: ")
+		io.flush()
+		local n = tonumber(io.read())
+		if n and n < 10 and n > 0 then
+			local i
+			if n < 4 then
+				i = n + 6
+			elseif n > 6 then
+				i = n - 6
+			else
+				i = n
+			end
+
+			if tonumber(board[i]) then
+				board[i] = "U"
+				break
+			end
+			print(n .. " is taken by " .. board[i] .. ". Try another position...")
+		else
+			print("Invalid input! Try a number between 1 and 9")
+		end
+	end
+end
+
+local function computerMove(board)
+	local function oppositeOf(i)
+		return i == 1 and 9
+				or i == 3 and 7
+				or i == 7 and 3
+				or i == 9 and 1
+				or i == 2 and 8
+				or i == 4 and 6
+				or i == 6 and 4
+				or 2
+	end
+
+	local function SelectAnything()
+		for j = 1, 9 do
+			if tonumber(board[j]) then
+				print("Selecting " .. j .. " as a last resort")
+				return j
+			end
+		end
+	end
+
+	local i
+
+	if tonumber(board[5]) then
+		i = 5
+	else
+		local r, map, c = math.floor(math.random(1, 4)), { 1, 3, 7, 9 }
+		c = board[map[r]]
+		if tonumber(c) then
+			i = map[r]
+		elseif c ~= "C" and tonumber(board[oppositeOf(map[r])]) then
+			i = oppositeOf(map[r])
+		else
+			map = { 2, 4, 6, 8 }
+			c = board[map[r]]
+			if tonumber(c) then
+				i = map[r]
+			elseif c ~= "C" and tonumber(board[oppositeOf(map[r])]) then
+				i = oppositeOf(map[r])
+			else
+				i = SelectAnything()
+			end
+		end
+	end
+
+	print("Computer chooses: " .. board[i])
+	board[i] = "C"
+end
+
+-- Main game loop
+local function game()
+	-- Initialize the board
+	local b = { "7", "8", "9", "4", "5", "6", "1", "2", "3" }
+
+	printBoard(b)
+
+	while true do
+		humanMove(b)
+
+		if checkWin(b, "U") then
+			print("Congratulations! You win!")
+			printBoard(b)
+			break
+		elseif boardFull(b) then
+			print("It's a tie!")
+			printBoard(b)
+			break
+		end
+
+		computerMove(b)
+
+		if checkWin(b, "C") then
+			print("Computer wins! Better luck next time.")
+			printBoard(b)
+			break
+		elseif boardFull(b) then
+			print("It's a tie!")
+			printBoard(b)
+			break
+		end
+
+		printBoard(b)
+	end
+end
+
+while true do
+	game()
+	io.write("Would you like to play again? (y/N) ")
+	io.flush()
+	if string.upper(io.read()) ~= "Y" then
+		break
+	end
+end