## HtDP Problem Set | ## Section 12 |

Problem 1:

Develop the function

Ansort-auction-records-by-bid. The function consumes a list of auction records and returns a list of auction records sorted in decreasing order by bid amount.auction recordis defined as follows:

`(define-struct auction (item id bid))`

An auction record is a structure

(make-auction String Number Number)

Problem 2:

Develop the functioncancel-sum. The function consumes a list of numbers. The function should produce a new list of numbers one longer in length than the original list. The new list should be the same as the old with with an additional number at the end that will cause the sum of the numbers in the new list to be zero.

Problem 3:

Develop the functionsearch-lolos. The function consumes a symbol and a list of list of symbols and returns true if the symbol is found anywhere in the original list of lists; otherwise, it returns false.

Problem 4:

Develop the functionexpand-lon. The function consumes a list of natural numbers and returns a new list of natural numbers with each number in the original list replaced by a number of copies of that number equal to its value. For example, the function called with the list containing one and two would produce the list containing one, two, and two.

Problem 5:

Develop the functioncomplete-polygon. The function consumes a list of posns and a symbol representing a color and draws lines from every posn to every other posn. Be sure to load the draw teachpack before testing.

Jamie Raymond | Matthias Felleisen |

01 december 2003 |