Do While Loop for Allocating Remainder of Macro Variable

[jblogan]

I am coding a distribution of flu vaccine. I allocate this vaccine to individual providers based on what they've ordered via various steps (for example, step 1 is allocating 10 doses of vaccine to providers who ordered < 500; step 2 is allocating 50 doses of vaccine to providers who ordered >= 500, etc). 

I have reached the end of my distribution and am left with a macro variable that is the remainder of doses (in this case, 160). I have updated each provider order based on steps 1-5 on the amount of vaccine I've already distributed and have an order_remaining - some provider orders have been completed (order_remaining = 0) and some provider orders are still in need of additional doses (order_remaining = 50). I've included a screenshot of part of my dataset below.

I would like to distribute the remainder (160 doses) to fulfill the lowest remaining orders while the remainder > 0 in step 6. 

My thought was to use a do-while loop like: 

data test;

set vaccine_distribution;

remainder = &remainder;

do while (remainder > 0);

step_6 = order_remaining;

remainder + (-step_6);

end;

run;

I want the code to distribute vaccine to the lowest volume of order_remaining in multiples of 10 while the remainder > 0. In the screenshot I've included and based on a remainder of 160, I would expect the orders of 30 and one of the orders of 50 to be completed with 40 vaccines remaining (i.e. 30, 30, 30, 50).

I can't find any examples online of using a do while loop with the condition decreasing (i.e. remainder is going down each loop) rather than increasing and can't get the above code to complete. 

Thanks for your help!

[Reeza]

Please post some sample data as TEXT not PDF or an attachment, and include what you want as the output. This should be relatively easy using a DO loop with a BY option to decrease it as you go.

[jblogan]

Remainder = 160.

So this is an example of the current dataset: 

Order_Amount	Step_1	Step_2	Step_3	Amount_Allocated	Order_Remaining
100	10	90	0	100	0
120	10	0	80	90	30
150	10	0	110	120	30
200	10	0	140	150	50
800	50	0	250	300	500
800	50	0	250	300	500

Desired Output: 

Order_Amount	Step_1	Step_2	Step_3	Amount_Allocated	Order_Remaining	Step_6
100	10	90	0	100	0	0
120	10	0	80	90	30	30
150	10	0	110	120	30	30
200	10	0	140	150	50	50
800	50	0	250	300	500	50
800	50	0	250	300	500	0

Step_6 would revert to 0 when the remainder = 0 because all 160 doses were allotted to earlier orders.