Q10

#include <stdio.h>

// A petrol pump has petrol and distance to next petrol pump
struct petrolPump
{
  int petrol;
  int distance;
};
typedef long long lli;
// The function returns starting point if there is a possible solution,
// otherwise returns -1
int printTour(struct petrolPump arr[], int n)
{
    // Consider first petrol pump as a starting point
    int start = 0;
    int end =  1;

    int curr_petrol = arr[start].petrol - arr[start].distance;

    /* Run a loop while all petrol pumps are not visited.
      And we have reached first petrol pump again with 0 or more petrol */
    while (end != start || curr_petrol < 0)
    {
        // If curremt amount of petrol in truck becomes less than 0, then
        // remove the starting petrol pump from tour
        while (curr_petrol < 0 && start != end)
        {
            // Remove starting petrol pump. Change start
            curr_petrol -= arr[start].petrol - arr[start].distance;
            start = (start + 1)%n;

            // If 0 is being considered as start again, then there is no
            // possible solution
            if (start == 0)
               return -1;
        }

        // Add a petrol pump to current tour
        curr_petrol += arr[end].petrol - arr[end].distance;

        end = (end + 1)%n;
    }

    // Return starting point
    return start;
}

int main()
{
    struct petrolPump arr[10];
  int n;
  int i;
  scanf("%d",&n);
  for(i=0;i<n;i++)
  {
      scanf("%d %d",&arr[i].petrol,&arr[i].distance);
  }
    int start = printTour(arr, n);

    (start == -1)? printf("No solution"): printf("%d", start+1);

    return 0;
}