IOI tour

View as PDF

Submit solution

Points: 10 (partial)
Time limit: 1.0s
Memory limit: 256M

Problem type
WCIPEG 2018 ECOO Qualifier

This year, the organizers for the IOIO or International Olympiad in Informatics of Ontario, the council known by their clever acronym OIOIO, Organization for International Olympiad in Informatics of Ontario, has decided to add a bit of spice to the programming competitions this year.

For this year's programming circuit, there will be M (1 \le M \le 30) international host cities, each hosting exactly one programming event. Each city, i, will be identified by its single non-space separated name, S_i, and will host a tournament for this year's circuit. Cities are inputted by order of their competition, with the first happening before the second.

All competitors will visit all host cities to participate in all competitions, flying to each host city after the other following the order of their tournaments. There are K (1 \le K \le 500) number of flights available. Each flight, f, will connect cities A_f and B_f with a cost of C_f (1 \le C_f \le 1\,000), meaning competitors can travel bidirectionally from A to B, B to A for C_f. Flights may connect cities that are not host cities, but must nonetheless be considered in travel plans, for connecting flights are possible. At most one flight will exist between any two cities. The total number of cities with flights is guaranteed to be at most 50.

Your task is to help out Ben Chau, an aspiring programmer who wishes to complete this year's circuit. Ben Chau will begin this year's circuit in Toronto. What is the minimal cost for Ben Chau to attend the programming competitions in all M host cities with K available flights? The cost is the sum of all his flight costs, including the final trip back to Toronto.

Input Specification

The first line of input will contain a single integer T (1 \le T \le 10), the number of cases.

The first line of each test case consists of two space separated integers, M (1 \le M \le 30) and K (1 \le K \le 500).
The next M lines each describe a city, with the ith city being named S_i, a string no more than 50 characters long, with no spaces.
The following K lines each describe a flight, with the ith flight connecting cities A_i and B_i with cost C_f (1 \le C_f \le 1\,000).

Output Specification

For each test case, output one integer: the minimal cost for Ben Chau to visit all programming competitions. Output -1 if it is impossible for Ben Chau to visit all competitions.

Sample Input

4 6
Toronto Boston 1
Boston Orlando 4
Toronto Orlando 5
Toronto Chicago 8
Miami Chicago 3
Boston Chicago 1
1 1
Toronto Newcastle-Upon-Tyne 1000
6 15
Toronto Calgary 223
Sudbury Iqaluit 507
Montreal Yellowknife 624
Winnipeg Montreal 340
ThunderBay Waterloo 640
ThunderBay Winnipeg 330
Iqaluit Edmonton 667
Montreal Ottawa 784
Sudbury Ottawa 202
Windsor Vancouver 777
Montreal St.John's 484
London Yellowknife 661
Ottawa Windsor 201
Sudbury Toronto 42
London Quebec 724

Sample Output


To complete the first test case most optimally: Ben Chau stays in Toronto for the first competition (+0). He flies directly to Boston. (+1). Flies Boston → Chicago → Miami for the third competition (+4). Flies Miami → Chicago → Boston → Orlando for the last competition (+8). He takes the direct flight back to Toronto (+5).
This yields a total cost of 0 + 1 + 4 + 8 + 5 = 18.

Ben Chau cannot reach London in the second case, so it is impossible.


There are no comments at the moment.