CODEWITHSUNDEEP
algorithmtime
jpiccolo
jpiccolo

Reputation: 778

Figure out if hours spanned is greater than 24

I don't know if am am loosing my mind or if this is even possible.

By the way, I am not using any standard libraries so this is not language dependent, hence why it's here and not on stackoverflow.

I have 2 time periods that are being passed to me in a int format.

1st period-
    Start Time:
    End Time:

2nd period-
    Start Time:
    End Time:

The Int's are minutes since midnight, so 7am would be 420 minutes.

So an example of a function I am trying to write is:

bool SpanMoreThan24Hours(int firstStartTime, int firstEndTime,
                         int secondStartTime, int secondEndTime)
{
    ....
}

I am not even sure this can be done.

P.S. Spanning midnight is fine, but it doesn't have to. Periods can't overlap.

So it could look like this:
420, 1140, 1260, 419
7am, 7pm,  9pm,  6:59am
- Valid
This would be valid since it doesn't span over 24 hours.

420, 1140, 1260, 421
7am, 7pm,  9pm,  7:01am
- Not valid

420, 60, 120, 419
7am, 1am,2am, 6:59am
- Valid

I have to make sure from 1st period start time till 2nd period end time is not over 24 hours.

Upvotes: 3

Views: 261

Answers (3)

daniloquio
daniloquio

Reputation: 3902

If a period can start on monday and end on wednesday, there is no solution to the problem; otherwise, here is some C# to you:

int MinutesBetweenTwoTimes(int time1, int time2)
{
    return time1 < time2 ? time2 - time1 : (1440-time1) + time2;
}

bool SpanMoreThan24Hours(int firstStartTime, int firstEndTime,
                         int secondStartTime, int secondEndTime)
{
    int totalSpannedTime = MinutesBetweenTwoTimes(firstStartTime, firstEndTime)
                           + MinutesBetweenTwoTimes(firstEndTime, secondStartTime) 
                           + MinutesBetweenTwoTimes(secondStartTime, secondEndTime);
    return totalSpannedTime > 1440;
}

Upvotes: 6

Chris Simmons
Chris Simmons

Reputation: 7266

If I read it right, I think this works, no?

bool SpanMoreThan24Hours(int firstStartTime, int firstEndTime,
                     int secondStartTime, int secondEndTime)
{

   // Logically, you'll only have a span > 24 hours if one of them spans midnight
   if ( firstStartTime > firstEndTime || secondStartTime > secondEndTime )
   {

       // Check for period overlap:
       // If the second period doesn't span midnight, this means the first does.
       // So check for overlap:
       if ( secondStartTime <= secondEndTime && firstEndTime > secondStartTime ) 
         throw new Exception ("Periods cannot overlap");

       // If *both* periods span midnight, this means they logically overlap.
       else if ( firstStartTime > firstEndTime && secondStartTime > secondEndTime )
         throw new Exception ("Periods cannot overlap");

      // If we get to here, we know that the periods don't overlap, yet they span midnight
      // The answer now is simply if the end of the second span is after the first begins
      return secondEndTime > firstStartTime;
   }

   // Neither period span midnight, so overlap check is a snap:
   if ( firstEndTime > secondStartTime ) 
     throw new Exception ("Periods cannot overlap");

   // No errors (no overlaps) and no midnight span means
   // the only logical result is that this is not > 24 hours
   return false;
}

Upvotes: 0

Megan Walker
Megan Walker

Reputation: 213

I may be misunderstanding, but couldn't you just check whether firstStartTime <= secondEndTime?

Upvotes: 0

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