COCI '20 Contest 4 #4 Janjetina
View as PDFAfter restaurants all over Croatia closed because of the lockdown, Mr. Malnar was first overwhelmed with sadness. But he soon realized that there was no point in being sad, and he decided that as soon as the restaurants reopen, he will travel around Croatia and treat himself with the best lamb Croatian restaurants can offer.
Mr. Malnar knows about  cities he could visit, that he labeled with integers from 
through 
. Also, he knows about 
 two-way roads that connect those cities, in such a way that it is
possible to travel between any two cities.
On every road there is a restaurant that serves lamb, and Mr. Malnar knows how many kilograms of lamb he can order in each one.
He will choose two different cities  and 
, and travel from 
 to 
 via the shortest path, i.e. the path
that uses the minimal number of roads. He will stop at exactly one restaurant, the one where he can
order the maximum amount of lamb (if there are multiple such restaurants, he will choose any of them),
and he will of course eat all the lamb he orders.
Mr. Malnar considers a path of length  on which he eats 
 kilograms of lamb to be satisfactory if
. The length of a path is equal to the number of roads that it goes through.
He wonders how many ordered pairs of distinct cities  there are, such that the shortest path from 
to 
 is satisfactory. He is very busy, so he asks you to calculate the answer for him.
Input Specification
The first line contains integers  and 
 
, the number of cities, and the satisfaction threshold.
Each of the following  lines contains three integers 
, 
 and 
 
, which means that there is a road that connects 
 and 
, and there is a restaurant on that road where Mr. Malnar can order 
 kilograms of lamb.
Output Specification
Output the number of ordered pairs of distinct cities , such that the shortest path from 
 to 
 is satisfactory.
Constraints
| Subtask | Points | Constraints | 
|---|---|---|
| Cities  | 
 ||
| No additional constraints. | 
Sample Input 1
3 2
1 2 3
1 3 2
Sample Output 1
2
Sample Input 2
4 1
1 2 1
2 3 2
3 4 3
Sample Output 2
6
Sample Input 3
5 2
1 2 2
1 3 3
3 4 2
3 5 4
Sample Output 3
8
Explanation for Sample 3
The pairs are , 
, 
, 
, 
, 
, 
 and 
.
Comments