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:

 License OUT @ 2008/10/03_23:51:05 for job 4974
 ...
 License IN  @ 2008/10/04_00:18:22 for job 4974



Task

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).




 
 PROGRAM MAX_LICENSES
   IMPLICIT NONE
 
   INTEGER :: out=0, maxout=0, maxcount=0, err
   CHARACTER(50) :: line
   CHARACTER(19) :: maxtime(100)
 
   OPEN (UNIT=5, FILE="Licenses.txt", STATUS="OLD", IOSTAT=err)
   IF (err > 0) THEN
     WRITE(*,*) "Error opening file Licenses.txt"
     STOP
   END IF
 
   DO 
     READ(5, "(A)", IOSTAT=err) line
     IF (err == -1) EXIT          ! EOF detected
     IF (line(9:9) == "O") THEN
       out = out + 1
     ELSE IF (line(9:9) == "I") THEN
       out = out - 1
     END IF
     IF (out > maxout ) THEN
       maxout = maxout + 1
       maxcount = 1
       maxtime(maxcount) = line(15:33)
     ELSE IF (out == maxout) THEN
       maxcount = maxcount + 1
       maxtime(maxcount) = line(15:33)
     END IF
   END DO
 
   CLOSE(5)
 
   WRITE(*,"(A,I4,A)") "Maximum simultaneous license use is", maxout, " at the following times:"
   WRITE(*,"(A)") maxtime(1:maxcount)
 
 END PROGRAM MAX_LICENSES
 