Make-change: Beginner Trouble

I'm trying to create "make-change" that will return a ls 开发者_运维百科of coins whose sum = the input, and it needs to contain the least number of coins possible. Ex: (make-change 99)

=> (quarter quarter quarter dime dime penny penny penny penny)

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Here's the lines along which make-change should operate:

• If the remaining amount is exactly equal to 1, 5, 10, or 25 then return the appropriate coin.
• Otherwise, cons the largest coin you can use onto the result of (make-change (- x value)) where value is the amount of the coin that you just used.

You can tell this procedure will terminate, since the amount will become smaller and smaller via step 2 until it is finally amenable to concluding with step 1.