Problem:
Single Source Shortest Path (Negative Edges)

Input

An edge-weighted graph G (V, E) and the source r.

|V| |E| r
s0 t0 d0
s1 t1 d1
:
s|E|-1 t|E|-1 d|E|-1

|V| is the number of vertices and |E| is the number of edges in G. The graph vertices are named with the numbers 0, 1,..., |V|-1 respectively. r is the source of the graph.

si and ti represent source and target vertices of i-th edge (directed) and di represents the cost of the i-th edge.

Output

If the graph contains a negative cycle (a cycle whose sum of edge costs is a negative value) which is reachable from the source r, print

NEGATIVE CYCLE

in a line.

Otherwise, print

c0
c1
:
c|V|-1

The output consists of |V| lines. Print the cost of the shortest path from the source r to each vertex 0, 1, ... |V|-1 in order. If there is no path from the source to a vertex, print "INF".

Constraints

1 ≤ |V| ≤ 1000

0 ≤ |E| ≤ 2000

-10000 ≤ di ≤ 10000

There are no parallel edges

There are no self-loops

Sample Input 1

4 5 0
0 1 2
0 2 3
1 2 -5
1 3 1
2 3 2

Sample Output 1

0
2
-3
-1

Sample Input 2

4 6 0
0 1 2
0 2 3
1 2 -5
1 3 1
2 3 2
3 1 0

Sample Output 2

NEGATIVE CYCLE

Sample Input 3

4 5 1
0 1 2
0 2 3
1 2 -5
1 3 1
2 3 2

Sample Output 3

INF
0
-5
-3

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace aoj_graph
{
    class Program
    {
        static void Main()
        {
            string[] ver = Console.ReadLine().Split(' ');
            int v = int.Parse(ver[0]);
            int e = int.Parse(ver[1]);
            int r = int.Parse(ver[2]);
            int[] dist = new int[v];
            int ma = v * 10000;
            bool nega = false;
            for (int i = 0; i < v; ++i)
                dist[i] = ma;

            dist[r] = 0;

            node[] n = new node[e];

            for (int i = 0; i < e; ++i) 
            {
                n[i] = new node();
            }

            List<node>[] l = new List<node>[v];
            for (int i = 0; i < v; ++i) 
            {
                l[i] = new List<node>();
            }

            
            for (int i = 0; i < e; ++i) 
            {
                string[] std = Console.ReadLine().Split(' ');
                int s = int.Parse(std[0]);
                int t = int.Parse(std[1]);
                int d = int.Parse(std[2]);
                n[i].target = t;
                n[i].cost = d;
                l[s].Add(n[i]);
            }

            
            node k = new node();
            k.target = r;
            k.cost = 0;

            for (int i = 0; i < v; ++i) 
            {
                for (int j = 0; j < v; ++j) 
                {
                    foreach (node p in l[j])
                    {
                        if (dist[j] < ma && (dist[p.target] >= ma || dist[j] + p.cost < dist[p.target]))
                        {
                            if (i < v - 1)
                                dist[p.target] = dist[j] + p.cost;
                            else
                            {
                                nega = true;
                                break;
                            }
                        }
                    }
                }
            }
            if (nega)
                Console.WriteLine("NEGATIVE CYCLE");
            else
            {
                foreach (int i in dist)
                {
                    if (i < ma)
                        Console.WriteLine(i.ToString());
                    else
                        Console.WriteLine("INF");
                }
            }

        }
        class node
        {
            public int target;
            public int cost;

        }

    }

}