Randomly distributing in dinamic array

I have a dynamic array and an Integer which has a value 3 times array length that is

Integer = array.length*3

For example if the array has 4 cells then the integers value is 12 and the distribution can be [8][1][2][1], [5][3][0][4], [0][12][0][0].

How can I distribute the Integer value between each cells of the array?