Quintiq Puzzle Competition Week #4

Start

2018-05-07 08:00 UTC

Quintiq Puzzle Competition Week #4

End

2018-05-14 08:00 UTC
The end is near!
Contest is over.
Not yet started.
Contest is starting in -322 days 13:46:14

Time elapsed

168:00:00

Time remaining

0:00:00

Problem D
A Walk Through The Forest

Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. To make things even nicer, his office is on one side of a forest, and his house is on the other. A nice walk through the forest, seeing the birds and chipmunks is quite enjoyable.

The forest is beautiful, and Jimmy wants to take a different route everyday. He also wants to get home before dark, so he always takes a path to make progress towards his house. He considers taking a path from $A$ to $B$ to be progress if there exists a route from $B$ to his home that is shorter than any possible route from $A$. Calculate how many different routes through the forest Jimmy might take.

Input

Input contains several test cases (at most $10$) followed by a line containing $0$. Jimmy has numbered each intersection or joining of paths starting with $1$. His office is numbered $1$, and his house is numbered $2$. The first line of each test case gives the number of intersections $N$, $1 < N \le 1000$, and the number of paths $M$. The following $M$ lines each contain a pair of intersections $a, b$ and an integer distance $1 \le d \le 1000000$ indicating a path of length $d$ between intersection $a$ and a different intersection $b$. Jimmy may walk a path any direction he chooses. There is at most one direct path between any pair of intersections.

Output

For each test case, output a single integer indicating the number of different routes through the forest. You may assume that this number does not exceed $2147483647$.

Sample Input 1 Sample Output 1
5 6
1 3 2
1 4 2
3 4 3
1 5 12
4 2 34
5 2 24
7 8
1 3 1
1 4 1
3 7 1
7 4 1
7 5 1
6 7 1
5 2 1
6 2 1
0
2
4