public find_tour_that_visits_all_stations()
{
/*
* Suppose there is a circle. There are n petrol pumps on that circle. You are given two sets of data.
* The amount of petrol that every petrol pump has.
* Distance from that petrol pump to the next petrol pump.
* Calculate the first point from where a truck will be able to complete the circle
* (The truck will stop at each petrol pump and it has infinite capacity).
* Expected time complexity is O(n). Assume for 1-litre petrol, the truck can go 1 unit of distance.
*
*
* petrolPump p1 = new petrolPump(4,6);
* petrolPump p2 = new petrolPump(6,5);
* petrolPump p3 = new petrolPump(7,3);
* petrolPump p4 = new petrolPump(4,5);
*/
petrolPump p1 = new petrolPump(4, 6);
petrolPump p2 = new petrolPump(6, 5);
petrolPump p3 = new petrolPump(7, 3);
petrolPump p4 = new petrolPump(4, 5);
List <petrolPump> list = new List <petrolPump>();
list.Add(p1);
list.Add(p2);
list.Add(p3);
list.Add(p4);
int res = find_dist(list);
}
int find_dist(List <petrolPump> list)
{
int start = 0, end = 1;
int cur = (list.ElementAt(start).petrol - list.ElementAt(start).distance);
// If current amount of petrol in
// truck becomes less than 0, then
// remove the starting petrol pump from tour
while (end != start && cur < 0)
{
// If current amount of petrol in
// truck becomes less than 0, then
// remove the starting petrol pump from tour
while (end != start && cur < 0)
{
// Remove starting petrol pump.
// Change start
cur = cur - (list.ElementAt(start).petrol - list.ElementAt(start).distance);
start = (start + 1) % list.Count;
// If 0 is being considered as
// start again, then there is no
// possible solution
if (start == 0)
{
return(-1);
}
}
petrolPump node = list.ElementAt(end);
// Add a petrol pump to current tour
cur += list.ElementAt(end).petrol - list.ElementAt(end).distance;
end = (end + 1) % list.Count;
}
return(start);
//int end = 1, start = 0;
//int cur = 0;
//int itr = 0;
//while(true)
//{
// Console.WriteLine("Checking index " + start);
// petrolPump obj = list.ElementAt(start);
// cur = cur+ (obj.petrol - obj.distance);
// if (cur < 0)
// {
// cur = 0;
// itr = 0;
// start++;
// }
// else
// {
// itr++;
// start++;
// }
// //if (start != 0 ? start + 1 == end : start == end)
// // break;
// if (start > list.Count - 1)
// start = 0;
// if (itr == list.Count)
// break;
//}
//if (cur>=0)
//{
// int res = end + 1;
//}
}