20481.c

// add your header comment here

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
// put any extra includes here, but don't delete the ones above

#define SIZE    4

// add your function_prototypes here

// The functions moveLeft, moveRight, moveUp, moveDown
// return -1 if the specified moving of numbers  is not possible.
// Otherwise they move the numbers as indicated and return
// the change to the score from combining adjacent identical numbers.
// They return 0 if no numbers were combined.

/*
    题目的意思是这样的，需要‘严格’判断能否移动，我用flag标示移动的时候在第二个判断的时候出错了！

    拿下移为例，if(cell==0)的时候直接判断可以移动是错误的，当下移的时候，如果只有

    上面第一行的某一个元素为0，下面所有行不出现合并的情况下是不能下移的。

        所以在上下左右移动的过程中，当if(cell==0)即当前元素为0时要使得能够移动，就必须限制这个为0的

    元素不是上面第一行（下移时）、左侧第一列（右移）、右侧第一列（左移）、下面第一行（上移）、

        所以修改每个move函数中判断if(cell==0)代码的i或者j的循环条件，以避开判断时0所在的特殊行位置

        具体修改看下面部分注释（修改的只有每个move函数中第二个for循环中的i或者j的循环条件）

*/

int moveLeft(int board[SIZE][SIZE]) {
    int i,j,score=0,flag=-1;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            int cell=board[i][j];//cell单词用的不太恰当，表示当前元素，你可以采用更有意义的命名
            if(cell!=0)
            {
                int k=j+1;
                while(k<SIZE)
                {
                    int nextcell=board[i][k];
                    if(nextcell!=0)
                    {
                        if(cell==nextcell)
                        {
                            flag=0;//相邻两个元素相同，就说明能移动，所以改变flag的值
                            board[i][j]+=board[i][k];
                            score+=board[i][j];
                            board[i][k]=0;
                        }
                        k=SIZE;
                        break;
                    }
                    k++;
                }
            }
        }
    }

    //修改部分：for循环中的i或者j的循环条件

    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE-1;j++)
        {
            int cell=board[i][j];
            if(cell==0)
            {
                int k=j+1;
                while(k<SIZE)
                {
                    int nextcell=board[i][k];
                    if(nextcell!=0)
                    {
                        flag=0;//
                        board[i][j]=nextcell;
                        board[i][k]=0;
                        k=SIZE;
                    }
                    k++;
                }
            }
        }
    }
    if(flag!=-1)
        return score;
    else
        return -1;
}

int moveRight(int board[SIZE][SIZE]) {
    int i,j,score=0,flag=-1;
    for(i=0;i<SIZE;i++)
    {
        for(j=SIZE-1;j>=0;j--)
        {
            int cell=board[i][j];
            if(cell!=0)
            {
                int k=j-1;
                while(k>=0)
                {
                    int nextcell=board[i][k];
                    if(nextcell!=0)
                    {
                        if(cell==nextcell)
                        {
                            flag=0;
                            board[i][j]+=board[i][k];
                            score+=board[i][j];
                            board[i][k]=0;
                        }
                        k=-1;
                        break;
                    }
                    k--;
                }
            }
        }
    }

     //修改部分：for循环中的i或者j的循环条件

    for(i=0;i<SIZE;i++)
    {
        for(j=SIZE-1;j>0;j--)
        {
            int cell=board[i][j];
            if(cell==0)
            {

                int k=j-1;
                while(k>=0)
                {
                    int nextcell=board[i][k];
                    if(nextcell!=0)
                    {
                        flag=0;//当前元素为0，说明能移动，改变flag的值
                        board[i][j]=nextcell;
                        board[i][k]=0;
                        k=-1;
                    }
                    k--;
                }
            }
        }
    }
    if(flag!=-1)
        return score;
    else
        return -1;
}

int moveDown(int board[SIZE][SIZE]) {
    int i,j,score=0,flag=-1;
    for(i=SIZE-1;i>=0;i--)
    {
        for(j=0;j<SIZE;j++)
        {
            int cell=board[i][j];

            if(cell!=0)
            {
                int k=i-1;
                while(k>=0)
                {
                    int nextcell=board[k][j];
                    if(nextcell!=0)
                    {
                        if(board[i][j]==board[k][j])
                        {
                            flag=0;
                            board[i][j]+=board[k][j];
                            score+=board[i][j];
                            board[k][j]=0;
                        }
                        k=0;
                        break;
                    }
                    k--;
                }
            }
        }
    }

     //修改部分：for循环中的i或者j的循环条件
    for(i=SIZE-1;i>0;i--)
    {
        for(j=0;j<SIZE;j++)
        {
            int cell=board[i][j];
            if(cell==0)
            {
                int k=i-1;
                while(k>=0)
                {
                    int nextcell=board[k][j];
                    if(nextcell!=0)
                    {
                        flag=0;
                        board[i][j]=nextcell;
                        board[k][j]=0;
                        k=0;
                    }
                    k--;
                }
            }
        }
    }
    if(flag!=-1)
        return score;
    else
        return -1;
}

int moveUp(int board[SIZE][SIZE]) {
   int i,j,score=0,flag=-1;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            int cell=board[i][j];

            if(cell!=0)
            {
                int k=i+1;
                while(k<SIZE)
                {
                    int nextcell=board[k][j];
                    if(nextcell!=0)
                    {
                        if(cell==nextcell)
                        {
                            flag=0;
                            board[i][j]+=board[k][j];
                            score+=board[i][j];
                            board[k][j]=0;
                        }
                        k=SIZE;
                        break;
                    }
                    k++;
                }
            }
        }
    }

     //修改部分：for循环中的i或者j的循环条件
    for(i=0;i<SIZE-1;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            int cell=board[i][j];
            if(cell==0)
            {

                int k=i+1;
                while(k<SIZE)
                {
                    int nextcell=board[k][j];
                    if(nextcell!=0)
                    {
                        flag=0;
                        board[i][j]=nextcell;
                        board[k][j]=0;
                        k=SIZE;
                    }
                    k++;
                }
            }
        }
    }
    if(flag!=-1)
        return score;
    else
        return -1;
}

// gameOver returns 0 iff it is possible to make a move on the board
// It returns 1 otherwise.

int gameOver(int board[SIZE][SIZE]) {
    int copy_board[SIZE][SIZE],i,j;
    /*为了避免直接把board[][]传进move函数判断的时候改变board，所以把board复制给
    另一个数组,然后判断，这样就不会改变board数组了

    */
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            copy_board[i][j]=board[i][j];
        }
    }
    if(moveDown(copy_board)==-1&&moveUp(copy_board)==-1&&moveLeft(copy_board)==-1&&moveRight(copy_board)==-1)//如果四个移动函数都返回-1即不能移动GameOver
        return 1;
    else
        return 0;

}

// boardContains2048 returns 1 iff the board contains 2048.
// It returns 0 otherwise.

int boardContains2048(int board[SIZE][SIZE]) {
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            if(board[i][j]==2048)
                return 1;
        }
    }
    return 0;
}

// printBoard displays the board.

void printBoard(int board[SIZE][SIZE]) {
    int i,j;

    printf("+");
    for(j=0;j<SIZE;j++)
    {
        printf("-----");
    }
    printf("+\n");

    for(i=0;i<SIZE;i++)
    {
        printf("|");
        for(j=0;j<SIZE;j++)
        {
            if(board[i][j]==0)
            {
                char a='.';
               printf("%5c",a);
            }
            else
            {
                 printf("%5d",board[i][j]);
            }
        }
        printf("|\n\n");
    }

    printf("+");
    for(j=0;j<SIZE;j++)
    {
        printf("-----");
    }
    printf("+\n");
}


// readBoard attempts to read SIZE*SIZE integers into array board
// it returns how many integers actually were read

int readBoard(int board[SIZE][SIZE]) {
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
            scanf("%d",&board[i][j]);
    }
    return i*j;
}

//
// add your functions here
//

//
// You do not need to modify the code below here.
//
// If you wish to modify the code below, you have
// misunderstood the assignment specification
//

void printHelp(void);
void insertNewNumber(int board[SIZE][SIZE]);

int main(int argc, char *argv[]) {
    int board[SIZE][SIZE] = {{0}};
    int c, score, moveScore, gameWon, numbersRead;
    unsigned int seed;

    // initialize random generator with command-line argument if provided
    // or with current time
    if (argc > 1){
        seed = atoi(argv[1]);
    } else {
        seed = time(0);
    }
    srand(seed);

    printf("Enter %d numbers making up initial board:\n", SIZE * SIZE);
    numbersRead = readBoard(board);
    if (numbersRead != SIZE * SIZE) {
        printf("Warning readBoard read only %d numbers\n", numbersRead);
    }

    printf("Repeat game by running: %s %u\n", argv[0], seed);
    printHelp();
    score = 0;
    gameWon = 0;
    while (gameOver(board) == 0) {
        printf("\n");
        printBoard(board);
        printf("Your score is %d.\n", score);
        if (gameWon == 0 && boardContains2048(board)) {
            gameWon = 1;
            printf("Congratulations you've won the game - q to quit or you can keep going\n");
        }
        printf("> ");

        c = getchar();
        while (c != EOF && isspace(c)) {
            c = getchar();
        }

        printf("\n");

        if (c == EOF || c == 'q' || c == 'Q') {
            printf("Good bye - your final score was %d.\n", score);
            return 0;
        }

        c = tolower(c);
        if (!strchr("hjklaswd", c)) {
            printHelp();
        } else {
            moveScore = 0;
            if (c == 'h' || c == 'a') {
                moveScore = moveLeft(board);
            } else if (c == 'j' || c == 's') {
                moveScore = moveDown(board);
            } else if (c == 'k' || c == 'w') {
                moveScore = moveUp(board);
            } else if (c == 'l' || c == 'd') {
                moveScore = moveRight(board);
            }

            if (moveScore == -1) {
                printf("%c is not a legal move in the current position.\n", c);
            } else {
                insertNewNumber(board);
                score = score + moveScore;
            }
        }
    }
    printBoard(board);
    printf("Game over - your final score was %d.\n", score);
    return 0;
}

// print a help message
// do not change this function

void
printHelp(void) {
    printf("Enter h or a for left, j or s for down, k or w for up, l or d for right, q to quit\n");
}


// add a new number to the board
// it will either be a 2 (90% probability) or a 4 (10% probability)
// do not change this function

void insertNewNumber(int board[SIZE][SIZE]) {
    int row, column;
    int index, availableSquares = 0;

    // count vacant squares
    for (row = 0; row < SIZE; row = row + 1) {
        for (column = 0; column < SIZE; column = column + 1) {
            if (board[row][column] == 0) {
                availableSquares = availableSquares + 1;
            }
        }
    }

    if (availableSquares == 0) {
        printf("Internal error no available square\n");
        exit(1);
    }

    // randomly pick a vacant square
    index = rand() % availableSquares;
    for (row = 0; row < SIZE; row = row + 1) {
        for (column = 0; column < SIZE; column = column + 1) {
            if (board[row][column] == 0) {
                if (index == 0) {
                    if (rand() % 10 == 0) {
                        board[row][column] = 4;
                    } else {
                        board[row][column] = 2;
                    }
                    return;
                }
                index = index - 1;
            }
        }
    }
}