Tetris (5)

1. Modify your previous TETRIS program, so that the 7 tetrominoes are stored in a struct array, instead of two independet arrays.
2. If you use an array max_x[7] to store the width of the 7 tetrominoes, try to replace it with a function max_x() to provide better flexibility. You'll need this when you want to rotate a tetromino.
3. If your program is well structured, you only need to modify the draw_block() function and erase_block() function.
4. Suppose you declare the struct as

   
   struct Square
   {
       int dx;
       int dy;
   };
   
   struct Tetromino
   {
       Square s[4];
   };
   
   Tetromino t[7] = {
                       0,0, 1,0, 2,0, 3,0 ,
                       0,0, 0,1, 1,1, 2,1 ,
                       0,1, 1,1, 2,1, 2,0 ,
                       0,0, 1,0, 0,1, 1,1 ,
                       0,1, 1,1, 1,0, 2,0 ,
                       0,1, 1,1, 1,0, 2,1 ,
                       0,0, 1,0, 1,1, 2,1
                    };
   
   

   You would be able to access the coordinate of Square j in Tetromino n as t[n].s[j].dy or t[n].s[j].dx.
5. The program should run as the same as the previous one. In this exercise, we simply replace the data structure from two integer arrays to a struct array, so that it will be easier to support the features required in the next version.