main.cpp

#include <iostream>
#include <string>
#include <iomanip>
#include <ctime>
#include <cstdlib>

using namespace std;

int board[4][4];
int dirLine[] = {1, 0, -1, 0};
int dirColumn[] = {0, 1, 0, -1};

pair<int,int> generateUnoccupiedPosition() {
    int occupied = 1, line, column;
    while (occupied) {
        line = rand() % 4;
        column = rand() % 4;
        if (board[line][column] == 0) {
            occupied = 0;
        }
    }
    return make_pair(line, column);
}

void addPiece() {
    pair<int, int> pos = generateUnoccupiedPosition();
    board[pos.first][pos.second] = 2;
}

void newGame() {
    for (int i = 0; i < 4; ++i) {
        for (int j = 0; j < 4; ++j) {
            board[i][j] = 0;
        }
    }
    addPiece();
}

void printUI() {
    system("clear");
;    for (int i = 0; i < 4; ++i) {
        for (int j = 0; j < 4; ++j) {
            if (board[i][j] == 0) {
                cout << setw(4) << ".";
            } else {
                cout << setw(4) << board[i][j];
            }
        }
        cout << "\n";
    }
    cout << "n: new game, w: up, s: down, d: right, a: left, q: quit\n";
}

bool canDoMove (int line, int column, int nextLine, int nextColumn) {
    if (nextLine < 0 || nextColumn < 0 || nextLine >= 4 || nextColumn >= 4 || (board[line][column] != board[nextLine][nextColumn] && board[nextLine][nextColumn] != 0)) {
        return false;
    }
    return true;
}

void applyMove (int direction) {
    int startLine = 0, startColumn = 0, lineStep = 1, columnStep = 1;
    if (direction == 0){
        startLine = 3;
        lineStep = -1;
    }
    if (direction == 1) {
        startColumn = 3;
        columnStep = -1;
    }
    int movePossible, canAddPiece = 0;
    do {
        movePossible = 0;
        for (int i = startLine; i >= 0 && i < 4; i += lineStep)
        {
            for (int j = startColumn; j >= 0 && j < 4; j += columnStep) {
                int nextI = i + dirLine[direction], nextJ = j + dirColumn[direction];
                if (board[i][j] && canDoMove(i, j, nextI, nextJ)) {
                    board[nextI][nextJ] += board [i][j];
                    board [i][j] = 0;
                    movePossible = canAddPiece = 1;
                }
            }
            printUI();
        }
    } while (movePossible);
    
    if (canAddPiece) {
        addPiece();
    }
    
}

int main()
{
    srand(time(0));
    char commandToDir[128];
    commandToDir['s'] = 0;
    commandToDir['d'] = 1;
    commandToDir['w'] = 2;
    commandToDir['a'] = 3;
    newGame();
    while (true) {
        printUI();
        char command;
        cin >> command;
        if (command == 'n') {
            newGame();
        } else if (command == 'q') {
            break;
        } else {
            int currentDirection = commandToDir[command];
            applyMove(currentDirection);
        }
    }
    return 0;
}