Create a Picture class that contains:

$1.$ a private vector of Pixel structures.

$2.$ a private integer representing the width of the picture.

$3.$ a private integer representing the height of the picture.

$4.$ a private integer representing the maximum intensity of each pixel color.

$5.$ a public constructor that takes no arguments. This constructor will set the width, height, and maximum intensity to $0.$

$6.$ a public accessor called get$\_$pixel. This function will take a row and a column as integer values, and it will return the given Pixel at the row and column by$-$constant$-$reference. You may assume that the row and column will exist. Remember, the private vector stores all pixel values in one dimension. This means that you'll need a little bit of math to figure out where the pixel begins. For this, remember that each row contains a number of pixels, which is equal to the number of columns. For example, a file that has a width of $10$ and a height of $5$ has $10$ columns and $5$ rows. This means that row$[0]$ starts at vector.at$(0)$ and row$[1]$ starts at vector.at$($total$\_$number$\_$of$\_$columns$)$ and row$[2]$ starts at vector.at$($total$\_$number$\_$of$\_$columns $*2)$;

$7.$ a public mutator also called get$\_$pixel. This function is exactly like the accessor get$\_$pixel, except it is a mutator, and allows for you to write set$\_$pixel by returning a mutable reference to a pixel.