How to resolve the algorithm Text processing/Max licenses in use step by step in the Racket programming language

Published on 12 May 2024 09:40 PM
#Racket

How to resolve the algorithm Text processing/Max licenses in use step by step in the Racket programming language

Table of Contents

Problem Statement

A company currently pays a fixed sum for the use of a particular licensed software package.   In determining if it has a good deal it decides to calculate its maximum use of the software from its license management log file. Assume the software's licensing daemon faithfully records a checkout event when a copy of the software starts and a checkin event when the software finishes to its log file. An example of checkout and checkin events are:

Save the 10,000 line log file from   here   into a local file, then write a program to scan the file extracting both the maximum licenses that were out at any time, and the time(s) at which this occurs. Mirror of log file available as a zip here (offsite mirror).

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Text processing/Max licenses in use step by step in the Racket programming language

Source code in the racket programming language

#lang racket
;;; reads a licence file on standard input
;;; returns max licences used and list of times this occurred
(define (count-licences)
  (let inner ((ln (read-line)) (in-use 0) (max-in-use 0) (times-list null))
    (if (eof-object? ln) 
        (values max-in-use (reverse times-list))
        (let ((mtch (regexp-match #px"License (IN |OUT) @ (.*) for job.*" ln)))
          (cond
            [(string=? "OUT" (second mtch))
             (let ((in-use+1 (add1 in-use)))
               (cond
                 [(> in-use+1 max-in-use)
                  (inner (read-line) in-use+1 in-use+1 (list (third mtch)))]
                 [(= in-use+1 max-in-use)
                  (inner (read-line) in-use+1 max-in-use (cons (third mtch) times-list))]
                 [else (inner (read-line) in-use+1 max-in-use times-list)]))]
            [(string=? "IN " (second mtch))
             (inner (read-line) (sub1 in-use) max-in-use times-list)]
            [else (inner (read-line) in-use max-in-use times-list)])))))

(define-values (max-used max-used-when)
(with-input-from-file "mlijobs.txt" count-licences))
(printf "Maximum licences in simultaneously used is ~a at the following times:~%"
        max-used)
(for-each displayln max-used-when)


#lang racket
;;; reads a licence file on standard input
;;; returns max licences used and list of times this occurred
(define (count-licences)
  (define (sub-count-licences)
    (for/fold ((in-use 0) (max-in-use 0) (times-list null))
      ((ln (in-lines)))
      (let ((mtch (regexp-match #px"License (IN |OUT) @ (.*) for job.*" ln)))
        (cond
          [(string=? "OUT" (second mtch))
           (let ((in-use+1 (add1 in-use)))
             (cond
               [(> in-use+1 max-in-use) (values in-use+1 in-use+1 (list (third mtch)))]
               [(= in-use+1 max-in-use) (values in-use+1 max-in-use (cons (third mtch) times-list))]
               [else (values in-use+1 max-in-use times-list)]))]
          [(string=? "IN " (second mtch)) (values (sub1 in-use) max-in-use times-list)]
          [else (values in-use max-in-use times-list)]))))
  (let-values (((in-use max-in-use times-list) (sub-count-licences)))
    (values max-in-use (reverse times-list))))

(define-values (max-used max-used-when) (with-input-from-file "mlijobs.txt" count-licences))
(printf "Maximum licences in simultaneously used is ~a at the following times:~%" max-used)
(for-each displayln max-used-when)

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