/*
* start: 6:38pm
*
* Need to write efficient interval algorithm
* No time out
* source code reference:
* 1. http://xiaoyaoworm.com/blog/2016/06/27/%E6%96%B0leetcode56-merge-intervals/
* 2. http://juliachencoding.blogspot.ca/2016/07/leetcode-56-merge-intervals.html
*
* end: 7:07
* walk through the code
*/
private static long increment(IList <Tuple <int, int> > intervals)
{
Tuple <int, int>[] sorted = intervals.ToArray();
IComparer <Tuple <int, int> > myComparer = new MyComparer();
Array.Sort(sorted, myComparer);
//Array.Reverse(arr);
Tuple <int, int> curr = sorted[0];
long sum = 0;
for (int i = 1; i < sorted.Length; i++)
{
Tuple <int, int> runner = sorted[i];
if (curr.Item2 < runner.Item1)
{
sum += curr.Item2 - curr.Item1 + 1;
curr = runner;
}
int start = curr.Item1;
int end = Math.Max(curr.Item2, runner.Item2);
curr = new Tuple <int, int>(start, end);
}
// edge case:
sum += curr.Item2 - curr.Item1 + 1;
return(sum);
}
/*
* train tracks on same row
* - merge intervals - train track stands for one interval
* - sort train tracks by start column
* - the array is based on start index 1 not 0
* Add all cells taken by train tracks on the same row.
*/
private static long SumCellsTakenByTrainTracksForSameRow(IList <Tuple <int, int> > trainTrackOnSameRow)
{
var trainTracks = trainTrackOnSameRow.ToArray();
IComparer <Tuple <int, int> > myComparer = new MyComparer();
Array.Sort(trainTracks, myComparer);
var previous = trainTracks[0];
long cellsTakensByTrainTracks = 0;
for (int i = 1; i < trainTracks.Length; i++)
{
var current = trainTracks[i];
// no overlap
if (previous.Item2 < current.Item1)
{
cellsTakensByTrainTracks += previous.Item2 - previous.Item1 + 1;
previous = current;
}
// reset the previous
int start = previous.Item1;
int end = Math.Max(previous.Item2, current.Item2);
previous = new Tuple <int, int>(start, end);
}
// edge case: Last one
cellsTakensByTrainTracks += previous.Item2 - previous.Item1 + 1;
return(cellsTakensByTrainTracks);
}