/**

* Java. Level 1. Lesson 4. Example of homework

* Tic-tac-toe in console with simple AI

*

* @author Sergey Iryupin

* @version dated Jun 15, 2019

*/

import java.util.Random;

import java.util.Scanner;

class HW4Lesson {

final int SIZE = 3; // size of the game map

final int WIN_SIZE = 3; // size of win-line

final char DOT_X = 'x'; // sign of human

final char DOT_O = 'o'; // sign of AI

final char DOT_EMPTY = '.'; // sign of empty cell

final String MSG_FOR_HUMAN = "Enter X and Y (1..3):";

final String MSG_YOU_WON = "YOU WON!";

final String MSG_AI_WON = "AI WON!";

final String MSG_DRAW = "Sorry, DRAW!";

final String MSG_GAME_OVER = "GAME OVER.";

char[][] map;

Scanner sc;

Random rand;

public static void main(String[] args) {

new HW4Lesson().game();

}

HW4Lesson() {

map = new char[SIZE][SIZE];

sc = new Scanner(System.in);

rand = new Random();

}

void game() {

initMap();

while (true) {

printMap();

turnHuman(DOT_X);

if (checkWin(DOT_X)) {

System.out.println(MSG_YOU_WON);

break;

}

if (isMapFull()) {

System.out.println(MSG_DRAW);

break;

}

turnAI(DOT_O, DOT_X);

//printMap();

if (checkWin(DOT_O)) {

System.out.println(MSG_AI_WON);

break;

}

if (isMapFull()) { // this code doesn't matter

System.out.println(MSG_DRAW); // because a human always

break; // makes a move last in 3x3

}

}

System.out.println(MSG_GAME_OVER);

printMap();

}

void initMap() { // init game's field

for (int i = 0; i < SIZE; i++)

for (int j = 0; j < SIZE; j++)

map[i][j] = DOT_EMPTY;

}

void printMap() { // output game's field

for (int i = 0; i < SIZE; i++) {

for (int j = 0; j < SIZE; j++)

System.out.print(map[i][j] + " ");

System.out.println();

}

System.out.println();

}

void turnHuman(char dot) { // human action

int x, y;

do {

System.out.println(MSG_FOR_HUMAN);

x = sc.nextInt() - 1;

y = sc.nextInt() - 1;

} while (!isCellValid(x, y));

map[y][x] = dot;

}

void turnAI(char dot, char enemyDot) { // AI action

int x, y;

for (x = 0; x < SIZE; x++) // simple blocking

for (y = 0; y < SIZE; y++)

if (isCellValid(x, y)) { // if cell empty

map[y][x] = enemyDot; // try to be like enemy

if (checkWin(enemyDot)) { // if win

map[y][x] = dot; // block

return; // and exit

}

map[y][x] = DOT_EMPTY; // restore cell

}

do {

x = rand.nextInt(SIZE);

y = rand.nextInt(SIZE);

} while (!isCellValid(x, y));

map[y][x] = dot;

}

boolean checkWin(char dot) { // check win condition

for (int y = 0; y < SIZE; y++)

for (int x = 0; x < SIZE; x++)

for (int dy = -1; dy < 2; dy++)

for (int dx = -1; dx < 2; dx++)

if (checkLine(x, y, dx, dy, dot) == WIN_SIZE)

return true;

/* simple checking of win in 3x3 map

// check horizontals and verticals

for (int i = 0; i < SIZE; i++)

if ((map[i][0] == dot && map[i][1] == dot && map[i][2] == dot) ||

(map[0][i] == dot && map[1][i] == dot && map[2][i] == dot))

return true;

// check diagonals

if ((map[0][0] == dot && map[1][1] == dot && map[2][2] == dot) ||

(map[2][0] == dot && map[1][1] == dot && map[0][2] == dot))

return true;

*/

return false;

}

int checkLine(int x, int y, int dx, int dy, char dot) {

int count = 0; // check line for win

if (dx == 0 && dy == 0)

return 0;

for (int i = 0, xi = x, yi = y;

i < WIN_SIZE; i++, xi += dx, yi += dy)

if (xi >= 0 && yi >= 0 && xi < SIZE &&

yi < SIZE && map[yi][xi] == dot)

count++;

return count;

}

boolean isMapFull() { // check field filling

for (int i = 0; i < SIZE; i++)

for (int j = 0; j < SIZE; j++)

if (map[i][j] == DOT_EMPTY)

return false;

return true;

}

boolean isCellValid(int x, int y) { // check cell

if (x < 0 || y < 0 || x >= SIZE || y >= SIZE)

return false;

return map[y][x] == DOT_EMPTY; // by DSerov

}

}