How to implement a 96 conditions wisely? - c++

Question

I'm trying to write a program in c++ which produce a report, which provide a report on the usage by time. Break the time into blocks of quarter of an hour
00:00-00:14, 00:15-00:29, …, 23:45-23:59.
I should provide number of incidents in each time break. This is my code so far. I appreciate if anyone come up with a solution.
string time = word;
size_t found2 = word.find(":");
string tmpH,tmpM;
tmpH = word.substr(0,found2);
tmpM = word.substr((found2+1),word.length());
cout<<" word= "<<word<<" tmpH= "<<tmpH<<" tmpM= "<<tmpM<<endl;
int h = atoi(tmpH.c_str());
int m = atoi(tmpM.c_str());
////
Input:
aa784 pts/30 Fri Mar 28 03:25 still logged in 101.175.22.198
aa784 sshd Fri Mar 28 03:25 still logged in 101.175.22.198
aa784 pts/30 Fri Mar 28 03:25 - 03:25 (00:00) 101.175.22.198
aa784 sshd Fri Mar 28 03:25 - 03:25 (00:00) 101.175.22.198
hmb183 sshd Fri Mar 28 03:24 still logged in c110-20-244-248.mirnd4.nsw.optusnet.com.au
bkg988 sshd Fri Mar 28 03:24 - 03:24 (00:00) 139.218.157.100
hmb183 sshd Fri Mar 28 03:21 - 03:22 (00:01) c110-20-244-248.mirnd4.nsw.optusnet.com.au
fmm290 pts/43 Fri Mar 28 03:11 still logged in 1002-wan-001.rhw.com.au
fmm290 sshd Fri Mar 28 03:11 still logged in 1002-wan-001.rhw.com.au
bkg988 sshd Fri Mar 28 03:09 - 03:09 (00:00) 139.218.157.100
pm554 pts/14 Fri Mar 28 02:22 still logged in ppp239-204.static.internode.on.net
pm554 sshd Fri Mar 28 02:22 still logged in ppp239-204.static.internode.on.net
bkg988 sshd Fri Mar 28 02:17 - 02:17 (00:00) 139.218.157.100
bkg988 sshd Fri Mar 28 02:12 - 02:12 (00:00) 139.218.157.100
bkg988 sshd Fri Mar 28 02:10 - 02:10 (00:00) 139.218.157.100
bx972 pts/12 Fri Mar 28 02:09 still logged in cpe-121-218-195-236.lnse4.cht.bigpond.net.au
bkg988 sshd Fri Mar 28 02:07 - 02:07 (00:00) 139.218.157.100
hmb183 sshd Fri Mar 28 02:05 - 02:06 (00:01) c110-20-244-248.mirnd4.nsw.optusnet.com.au
bkg988 sshd Fri Mar 28 02:04 - 02:04 (00:00) 139.218.157.100
output:
00:00-00:14 10 users logged in
00:15-00:29 15 users logged in
....
23:45-23:59 3 users logged in
Therefore I have 4 conditions in an hour which comes to 96 conditions of time?

Answer 1

First, you can convert each block of hour and minute into minutes , for example 23:45 equals 1095 in minutes. Storing all of these blocks into a list and sort them by its starting time.
For each event, convert each event time into number of minute and use binary search(or linear search) to search for a block that has largest starting time less than or equals to the event time,and that block will be the block this event belong to.
Time complexity to sort is O(1) as there is only few block, and, for all query will be O(n), with n is the number of query.(Binary search in this case can be considered take constant time).
Edit: As you have added another constraint, so , you need to sort all the event by date and time, and for each date, you can use the described approach.

Answer 2

Given lines like:
bkg988 sshd Fri Mar 28 02:17 - 02:17 (00:00) 139.218.157.100
You can do this:
std::string to_month_number(const std::string& name)
{
return name == "Jan" ? "01/" :
name == "Feb" ? "02/" :
...;
}
typedef std::pair<std::string, int> When;
typedef std::map<When, int> Num_Logins;
Num_Logins num_logins;
std::string user, term, day, month, dom;
int hour, min;
char c;
while (std::cin >> user >> term >> dow >> month >> dom >> hour >> c >> min && c == ':')
{
if (dom.length() == 1) dom = ' ' + dom; // standardise with for sorting...
When when = std::make_pair(to_month_number(month) + ' ' + dom, (hour * 60 + min) / 15);
++num_logins[when];
}
I suspect the actual input will be a bit more complex, with the date being formatted differently when the process started last year or intraday, so you'll need to tune the fields parsed out. To recreate the time when iterating over num_logins to print out results, just:
int hour = key->second / 4;
int min = (key->second % 4) * 15; // 00, 15, 30 or 45