;; The first three lines of this file were inserted by DrRacket. They record metadata ;; about the language level of this file in a form that our tools can easily process. #reader(lib "htdp-beginner-reader.ss" "lang")((modname total-sales-seats-matrix) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ()))) ;**************************************************************** ;; Developing a web application for reserving seats in a performing ;; arts center. The center has 504 seats, arranged in rows with 42 seats ;; in each row. The price for seats in the first four rows (#1 - #168) ;; is $200. The price for seats in the next four rows (#169 - #336) is ;; $100. The price for remaining seats is $75. ;; seat-price : Number -> Number ;; given seat number, produces the price of the seat (check-expect (seat-price 4) 200) (check-expect (seat-price 160) 200) (check-expect (seat-price 168) 200) (check-expect (seat-price 169) 100) (check-expect (seat-price 200) 100) (check-expect (seat-price 336) 100) (check-expect (seat-price 337) 75) (check-expect (seat-price 500) 75) (define (seat-price num) (cond [(<= 1 num 168) 200] [(<= 169 num 336) 100] [(<= 337 num 504) 75])) ;; A SeatingChart is a List-of-list-of-seats ;; A Seat is (make-seat Number Boolean) (define-struct seat (number reserved?)) ;; A List-of-seats is ; empty ; (cons seat list-of-seats) #|TEMPLATE ; los-func : list-of-seats ... -> ... ; purpose ... (check-expect (los-func ...)) (define (los-func a-los ...) (cond [(empty? a-los) ...] [(cons? a-los) ... (seat-func (first a-los)) ... (los-func (rest a-los) ...)] ) ) |# ;; A List-of-list-of-seats is either: ; empty ; (cons list-of-seats list-of-list-of-seats) #|TEMPLATE ; lolos-func : list-of-list-of-seats ... -> ... ; purpose ... (check-expect (lolos-func ...)) (define (lolos-func a-lolos ...) (cond [(empty? a-lolos) ...] [(cons? a-lolos) ... (los-func (first a-lolos)) ... (lolos-func (rest a-lolos) ...)] ) ) |# ;; small example: (define CHART1 (list (list (make-seat 1 false) (make-seat 2 false) (make-seat 3 false)) (list (make-seat 4 false) (make-seat 5 false) (make-seat 6 false) (make-seat 7 false)) (list (make-seat 8 false) (make-seat 9 false)))) (define CHART2 (list (list (make-seat 1 false) (make-seat 2 false) (make-seat 3 false)) (list (make-seat 4 false) (make-seat 5 false) (make-seat 6 false)) (list (make-seat 7 false) (make-seat 8 false) (make-seat 9 false)))) (define CHART3 (list (list (make-seat 1 false) (make-seat 2 false) (make-seat 3 true)) (list (make-seat 4 false) (make-seat 5 true) (make-seat 6 false) (make-seat 7 true)) (list (make-seat 8 true) (make-seat 9 false)))) ; available-seats : list-of-list-of-seats -> number ; consumes a seating chart and produces the number of unreserved seats (check-expect (available-seats CHART1) 9) (check-expect (available-seats CHART2) 9) (check-expect (available-seats CHART3) 5) (define (available-seats a-lolos) (cond [(empty? a-lolos) 0] [(cons? a-lolos) (+ (number-open (first a-lolos))(available-seats (rest a-lolos)))] ) ) ; number-open : list-of-seats -> number ; produces the number of open seats (check-expect (number-open (list (make-seat 1 false))) 1) (check-expect (number-open (list (make-seat 1 true))) 0) (check-expect (number-open (list (make-seat 1 false) (make-seat 2 false))) 2) (check-expect (number-open (list (make-seat 1 false) (make-seat 2 true))) 1) (define (number-open a-los) (cond [(empty? a-los) 0] [(cons? a-los) (cond [(seat-reserved? (first a-los)) (number-open (rest a-los))] [else (+ 1 (number-open (rest a-los))) ])] ) ) ; total-sales : list-of-list-of-seats -> number ; to produce the total amount of income made from seat sales (check-expect (total-sales CHART1) 0) (check-expect (total-sales CHART3) 800) (check-expect (total-sales (append CHART1 (list (list (make-seat 180 true) (make-seat 500 true))))) 175) (define (total-sales a-lolos) (cond [(empty? a-lolos) 0] [(cons? a-lolos) (+ (row-profit (first a-lolos)) (total-sales (rest a-lolos)))] ) ) ; row-profit : list-of-seats -> number ; determine the profit for the row (check-expect (row-profit (list (make-seat 1 false))) 0) (check-expect (row-profit (list (make-seat 1 true))) 200) (check-expect (row-profit (list (make-seat 1 true) (make-seat 169 true))) 300) (check-expect (row-profit (list (make-seat 200 true) (make-seat 500 true))) 175) (check-expect (row-profit (list (make-seat 200 false) (make-seat 500 true))) 75) (define (row-profit a-los) (cond [(empty? a-los) 0] [(cons? a-los) (cond [(seat-reserved? (first a-los)) (+ (seat-price (seat-number (first a-los))) (row-profit (rest a-los)))] [else (row-profit (rest a-los))])] ) ) (require (planet nah22/racketui)) (web-launch "Total Sales" (function "Computer total amount of income made from seat sales" (total-sales ["Stadium" (listof ["Row" (listof ["Seat" (structure make-seat ["Seat number" number] ["Reserved?" boolean])])])] -> ["Total sales" number])))