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.IO;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;

// Bellman-Ford O(|V| * |E|)
class Program
{
    static void Main()
    {
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        Console.SetOut(sw);
        new Program().solve();
        Console.Out.Flush();
    }
    Scanner cin = new Scanner();

    struct Edge
    {
        public int from, to, cost;
        public Edge(int from, int to, int cost)
        {
            this.from = from;
            this.to = to;
            this.cost = cost;
        }
    }

    void solve()
    {
        int V = cin.nextint;
        int E = cin.nextint;
        int r = cin.nextint;

        var G = new Edge[E];
        for (int i = 0; i < E; i++)
        {
            G[i] = new Edge(cin.nextint, cin.nextint, cin.nextint);
        }

        var D = Enumerable.Repeat(int.MaxValue, V).ToArray();

        D[r] = 0;
        for (int i = 0; i < V; i++)
        {
            for (int j = 0; j < E; j++)
            {
                var e = G[j];
                if (D[e.from] != int.MaxValue && D[e.to] > D[e.from] + e.cost)
                {
                    D[e.to] = D[e.from] + e.cost;

                    if (i == V - 1)
                    {
                        Console.WriteLine("NEGATIVE CYCLE");
                        return;
                    }
                }          
            }
        }

        foreach (var v in D)
        {
            Console.WriteLine(v == int.MaxValue ? "INF" : v + "");
        }
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan { get { return Console.ReadLine().Split(); } }
    public int[] scanint { get { return Array.ConvertAll(scan, int.Parse); } }
    public long[] scanlong { get { return Array.ConvertAll(scan, long.Parse); } }
    public double[] scandouble { get { return Array.ConvertAll(scan, double.Parse); } }
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = Console.ReadLine();
            while (st == "") st = Console.ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint { get { return int.Parse(next); } }
    public long nextlong { get { return long.Parse(next); } }
    public double nextdouble { get { return double.Parse(next); } }
}