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).




 
filename = "mlijobs.txt"
io.input( filename )
 
max_out, n_out = 0, 0
occurr_dates = {}
 
while true do
    line = io.read( "*line" )
    if line == nil then break end
 
    if string.find( line, "OUT" ) ~= nil then
        n_out = n_out + 1
        if n_out > max_out then
            max_out = n_out
            occurr_dates = {}
            occurr_dates[#occurr_dates+1] = string.match( line, "@ ([%d+%p]+)" )
        elseif n_out == max_out then
            occurr_dates[#occurr_dates+1] = string.match( line, "@ ([%d+%p]+)" )
        end
    else
        n_out = n_out - 1
    end
end
 
print( "Maximum licenses in use:", max_out )
print( "Occurrences:" )
for i = 1, #occurr_dates do
    print( "", occurr_dates[i] )
end