写一个数独游戏的代码，但是没啥思路。
用户能通过输入坐标来填充想写的数字（不是找数独答案的程序，是那种用户能玩的数独游戏代码）， 想不出咋写，能不能帮忙写一个
目前只学到二维数组，求大佬帮忙

比如说一个9*9的大小里，该咋让电脑在几个随机格子里填充1~9范围的随机数

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void genSuDo()
{
    int i, j, k, a, b;
    static int array[][9] = 
    {
        7,8,9, 3,1,4, 6,5,2,
        1,2,6, 8,7,5, 3,9,4,
        5,4,3, 2,9,6, 7,1,8,

        6,7,2, 1,5,3, 8,4,9,
        4,9,1, 7,6,8, 2,3,5,
        8,3,5, 4,2,9, 1,6,7,

        3,1,7, 9,4,2, 5,8,6,
        9,5,8, 6,3,7, 4,2,1,
        2,6,4, 5,8,1, 9,7,3
    };

    srand(time(0));

    for (k=0; k<5; k++)
    {
        a = (rand()%9) + 1;
        b = (rand()%9) + 1;
        for (i=0; i<9; i++)
        {
            for (j=0; j<9; j++)
            {
                if (array[i][j] == a)
                {
                    array[i][j] = b;
                }
                else if (array[i][j] == b)
                {
                    array[i][j] = a;
                }
            }
        }
    }

    a = rand()%3;
    b = (a+1+rand()%2)%3;
    for (i=0; i<3; i++)
    {
        for (j=0; j<9; j++)
        {
            array[a*3+i][j] ^= array[b*3+i][j];
            array[b*3+i][j] ^= array[a*3+i][j];
            array[a*3+i][j] ^= array[b*3+i][j];
        }
    }

    a = rand()%3;
    b = (a+1+rand()%2)%3;
    for (i=0; i<3; i++)
    {
        for (j=0; j<9; j++)
        {
            array[j][a*3+i] ^= array[j][b*3+i];
            array[j][b*3+i] ^= array[j][a*3+i];
            array[j][a*3+i] ^= array[j][b*3+i];
        }
    }

    for (i=0; i<9; i+=3)
    {
        a = rand()%3;
        b = (a+1+rand()%2)%3;
        for (j=0; j<9; j++)
        {
            array[i+a][j] ^= array[i+b][j];
            array[i+b][j] ^= array[i+a][j];
            array[i+a][j] ^= array[i+b][j];
        }
        a = rand()%3;
        b = (a+1+rand()%2)%3;
        for (j=0; j<9; j++)
        {
            array[j][i+a] ^= array[j][i+b];
            array[j][i+b] ^= array[j][i+a];
            array[j][i+a] ^= array[j][i+b];
        }
    }

    for (i=0; i<9; i++)
    {
        for (j=0; j<9; j++)
        {
            if (rand()%2 == 0)
            {
                printf("_ ");
            }
            else
            {
                printf("%d ", array[i][j]);
            }
        }
        printf("\n");
    }

    printf("\n\n");
}
void main()
{
    genSuDo();
}