tictactoe/game/ai.cpp

#include "ai.hpp"

std::random_device rd;
std::mt19937 mt(rd());

void aiTurn(map *m)
{
    std::uniform_int_distribution<int> dist(0, m->size - 1);

    if (aiWinCheck(m)) return;
    if (humWinCheck(m)) return;
    int x;
    int y;
    do {
        y = dist(mt);
        x = dist(mt);
    } while (m->cells[x][y]->p != EMPTY);
    setVal(m->cells[x][y], AI, true);
}

bool aiWinCheck(map *m)
{
    for (int y = 0; y < m->size; y++)
    {
        for (int x = 0; x < m->size; x++)
        {
            cell *c = m->cells[y][x];

            if (c->p == EMPTY)
            {
                setVal(c, AI, true);
                if (checkWin(m, AI))
                    return true;
                setVal(c, EMPTY);
            }
        }
    }
    return false;
}

bool humWinCheck(map *m)
{
    for (int y = 0; y < m->size; y++)
    {
        for (int x = 0; x < m->size; x++)
        {
            cell *c = m->cells[y][x];

            if (c->p == EMPTY)
            {
                setVal(c, HUMAN, true);
                if (checkWin(m, HUMAN))
                {
                    setVal(c, AI, true);
                    return true;
                }
                setVal(c, EMPTY);
            }
        }
    }

    return false;
}

void setVal(cell *c, PLAYER p, bool draw)
{
    c->p = p;
    c->is_draw = draw;
}

bool checkWin(map *m, PLAYER p)
{
    for (int y = 0; y < m->size; y++)
    {
        for (int x = 0; x < m->size; x++)
        {
            if (m->cells[y][x]->p == EMPTY) continue;
            if (checkLine(m, y, x, 0, 1, m->toWin, p)) return true;
            if (checkLine(m, y, x, 1, 1, m->toWin, p)) return true;
            if (checkLine(m, y, x, 1, 0, m->toWin, p)) return true;
            if (checkLine(m, y, x, -1, 1, m->toWin, p)) return true;
        }
    }

    return false;
}

bool checkLine(map *m, int y, int x, int vy, int vx, int len, PLAYER p)
{
    const int endX = x + (len - 1) * vx;
    const int endY = y + (len - 1) * vy;

    if (!isValid(m, endX, endY))
        return false;

    for (int i = 0; i < len; i++)
    {
        if (m->cells[y + i * vy][x + i * vx]->p != p)
            return false;
    }

    return true;
}

bool isValid(map *m, int y, int x)
{
    return CHECK_DOT(y, m->size) && CHECK_DOT(x, m->size);
}

bool isDraw(map *m)
{
    for (int y = 0; y < m->size; y++)
        for (int x = 0; x < m->size; x++)
            if (m->cells[y][x]->p == EMPTY)
                return false;
    return true;
}