SHPATH - The Shortest Path


You are given a list of cities. Each direct connection between two cities has its transportation cost (an integer bigger than 0). The goal is to find the paths of minimum cost between pairs of cities. Assume that the cost of each path (which is the sum of costs of all direct connections belongning to this path) is at most 200000. The name of a city is a string containing characters a,...,z and is at most 10 characters long.

Input

 

s [the number of tests <= 10]
n [the number of cities <= 10000]
NAME [city name]
p [the number of neighbours of city NAME]
nr cost [nr - index of a city connected to NAME (the index of the first city is 1)]
           [cost - the transportation cost]
r [the number of paths to find <= 100]
NAME1 NAME2 [NAME1 - source, NAME2 - destination]
[empty line separating the tests]

 

Output

 

cost [the minimum transportation cost from city NAME1 to city NAME2 (one per line)]

 

Example

 

Input:
1
4
gdansk
2
2 1
3 3
bydgoszcz
3
1 1
3 1
4 4
torun
3
1 3
2 1
4 1
warszawa
2
2 4
3 1
2
gdansk warszawa
bydgoszcz warszawa

Output:
3
2

 

Warning: large Input/Output data, be careful with certain languages


hide comments
kygas: 2018-04-01 23:08:47

No, no, I am supposed to teach kids the Dijkstra, and I am using this problem as an example.
But I figured that a solution I wanted to use was gone... I am a kid myself and story on how I got to explain Dijkstra is long and not important, but I am not going to use that code in competition It's just for explaining Dijkstra or better to show how this problem is solved, no unfair advantage will be gained with that code, don't worry. :)
C++ is the language I need...

Last edit: 2018-04-01 23:12:19
nadstratosfer: 2018-04-01 04:03:58

A state competition in ripping off someone else's code? By what criteria a winner is determined there, kygas?

kygas: 2018-03-31 20:59:25

I need a solution to this problem, would someone mind posting a link to it for a short time since I need it for the Monday for the preparation for the state competition, thanks in advance. :)

anirudnits: 2018-01-31 19:36:10

@kmkhan_014 thanks :)

Shivam Gupta: 2017-12-20 22:03:26

For those using dijkstra, another optimization that nobody seems to have mentioned is that instead of running dijkstra for each source-dest pair, store all the queries and run dijkstra only once from each source vertex till all the dest. are found

tzolkat: 2017-11-14 03:00:45

I need a bigger file to test with.

jha_gaurav98: 2017-11-11 04:18:20

Don't perform the complete dijkstra...as soon as you remove the destination vertex from the heap just stop

Adrian Motulewicz: 2017-11-01 01:54:58

When I know that key node is satisfied? When can I break out of the Dijkstra? I wrote my code in java and I have problem with time :-(

Last edit: 2017-11-01 01:56:53
bani_raheja: 2017-10-28 22:07:59

ac in one go!
Just take care that you don't traverse the whole graph. As soon as the shortest distance of the key node is satisfied, break out of the Dijkstra algorithm and print the result

kmkhan_014: 2017-10-25 19:41:35

The edges are all directed. if assumed undirected the judge may throw TLE


Added by:Darek Dereniowski
Date:2004-05-10
Time limit:1.5s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource:DASM Programming League 2003 (problemset 11)