Floyd Warshall Algorithm for Shortest Path

Question 1

There are several problems in your code:

Overwritten mapping

Your int c is local variable of the for cycle which means the highest used mapping index doesn't survive to the next iteration, so the reading in next iteration overrides the previous one. So the distance matrix is not properly filled after data loading.

Solution: move the int c = 0; outside from the for loop.

Unidirectional roads

The roads are bidirectional in the instructions, but you register them only as unidirectional. As the consequence of that are higher on non-existent connections between towns.

Solution: add dist[map.get(text[0].charAt(1))][map.get(text[0].charAt(0))] = Integer.parseInt(text[1]); right after the similar one.

Besides these hard issues I have also couple hints for you. You do not have follow them but as if you want to improve your programming skills then you should think about them.

Messy code

Your code is hard to read, there are multiple restated information such as indicies, the solving process is in the single method etc. Such code is not only hard to read but also extremely hard to debug and fix. For your own good I recommend you to write it cleaner.

Algorithm efficiency

Floyd-Warshall's algorithm has a O(n^3) complexity. The size of problem (amount of towns) is A-M = 13. In this complexity it makes 13^3 = 2197 iterations. I know, it might not seem to be a lot, but consider the amount of tasks to solve in a given time limit.

I would recommend you to use Dijkstra's algorithm which has complexity O(|E| + |V|log|V|). In this task the worst case with some simplification is |E| = (|V|^2)/2, |V|=13. It means, that the final number of iterations is 5 (|V|^2 / 2 + |V|log|V|) = 5 (13^2 / 2 + 13 * log13) ~ 5 * 132 = 660. If I am not wrong and made any mistake, this is significantly less, especially when we consider the total amount of tasks.

Input reading

I might be wrong but I attended multiple programming contests and competitions and it never forced attendees to work with files. An input was always redirected from files to a standard input. I guess, that the main reason for this is a security, but the simplification is probably also highly beneficial.

Question 2

Well that question I got, I am starting to do SPOJ now, and I gotta admit it is pretty difficult later on, but I came across the same kind of question http://www.spoj.com/problems/SHPATH/ , I also used Floyd Warshall

    import java.util.*;

    public class Floydwarshall {


public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    String q = s.nextLine();
    for(int t=0;t<Integer.parseInt(q);++t){
        int n = Integer.parseInt(s.nextLine());
        int[][] cost = new int[n][n];
        for (int y = 0; y < n; ++y) {
            for (int x = 0; x < n; ++x) {
                cost[x][y] = 10000;
            }
        }
        Map<String, Integer> map = new TreeMap<String, Integer>();
        int c = 0;
        for (int i = 0; i < n; ++i) {
            String a = s.nextLine();
            if (!map.containsKey(a)) {
                map.put(a, c);
                c++;
            }
            int f = Integer.parseInt(s.nextLine());
            for (int j = 0; j < f; ++j) {
                String text[] = s.nextLine().split(" ");
                cost[map.get(a)][Integer.parseInt(text[0]) - 1] =
                        cost[Integer.parseInt(text[0]) - 1][map.get(a)] = Integer.parseInt(text[1]);
            }
        }
        for (int k = 0; k < map.size(); ++k) {
            for (int i = 0; i < map.size(); ++i) {
                for (int j = 0; j < map.size(); ++j) {
                    cost[i][j] = Math.min(cost[i][j], cost[i][k] + cost[k][j]);
                }
            }
        }
        int num = Integer.parseInt(s.nextLine());
        for (int i = 0; i < num; ++i) {
            String text[] = s.nextLine().split(" ");
            System.out.println(cost[map.get(text[0])][map.get(text[1])]);
        }
    }
}}

now it runs alright for the sample input, but when I hand it in, it gives me this

NZEC (non-zero exit code) - this message means that the program exited returning a value different from 0 to the shell. For languages such as C, this probably means you forgot to add "return 0" at the end of the program. For interpreted languages (including JAVA) NZEC will usually mean that your program either crashed or raised an uncaught exception. Problem is I cannot kind where it crashes or raises an uncaught exception since it
works with the sample input