[Misiur]

For future reference, there is a way without collection of iterators:

pawn Код:

new
    Matrix[X_SIZE][Y_SIZE],
    Iterator:Matrix<X_SIZE * Y_SIZE>
;

public OnGameModeInit()
{
    //Example cells:
    for(new x = 0; x != 3; ++x) {
        for(new y = 0; y != 3; ++y) {
            Matrix[x][y] = x * y;
            Iter_Add(Matrix, x * Y_SIZE + y);
        }
    }

    //Retrieving random cell:
    new 
        rnd = Iter_Random(Matrix),
        x = rnd / Y_SIZE,
        y = rnd % Y_SIZE
    ;
    
    printf("Cell at (%d, %d) value is equal %d", x, y, Matrix[x][y]);

    return 1;
}