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 static System.Console;
using static System.Convert;
using static System.Math;
//using Debug;
//using static System.Globalization.CultureInfo;
//using Edge = Pair<long, int>;
using System.Text;
class Program
{ 
    static void Main(string[] args)
    {
        Solve();
        //WriteLine(Solve());
    }
    static void Solve()
    {
        var nmr = Input.ar;
        var eg = new List<Pair<long, int, int>>(nmr[1]);
        while (nmr[1]-- > 0)
        {
            var i = Input.ar;
            eg.Add(new Pair<long, int, int>(i[2], i[0], i[1]));
        }
        long[] dist;
        if(!ShortestPath.BellmanFord(nmr[0],eg,nmr[2],out dist))
        { WriteLine("NEGATIVE CYCLE");return; }
        WriteLine(string.Join("\n", dist.Select(v=>v==long.MaxValue?"INF":v.ToString())));
    }
}

public class Input
{
    public static string read => ReadLine().Trim();
    public static int[] ar => read.Split(' ').Select(int.Parse).ToArray();
    public  static int num => ToInt32(read);
    public static long[] arL => read.Split(' ').Select(long.Parse).ToArray();
    public  static long numL => ToInt64(read);
    public static char[][] gred(int h) 
        => Enumerable.Repeat(0, h).Select(_ => read.ToCharArray()).ToArray();
    public static int[] ar1D(int n)
        => Enumerable.Repeat(0, n).Select(_ => num).ToArray();
    public static long[] arL1D(int n)
        => Enumerable.Repeat(0, n).Select(_ => numL).ToArray();
    public static string[] strs(int n)
        => Enumerable.Repeat(0, n).Select(_ => read).ToArray();
    public static int[][] ar2D(int n)
        => Enumerable.Repeat(0, n).Select(_ => ar).ToArray();
    public static long[][] arL2D(int n)
        => Enumerable.Repeat(0, n).Select(_ => arL).ToArray();
    public static T getValue<T>(string g)
    {
        var t = typeof(T);
        if (t == typeof(int))
            return (T)(object)int.Parse(g);
        if (t == typeof(long))
            return (T)(object)long.Parse(g);
        if (t == typeof(string))
            return (T)(object)g;
        if (t == typeof(char))
            return (T)(object)char.Parse(g);
        if (t == typeof(double))
            return (T)(object)double.Parse(g);
        if (t == typeof(bool))
            return (T)(object)bool.Parse(g);
        return default(T);
    }
    public const long Inf = (long)1e18;
    public const double eps = 1e-6;
    public  const string Alfa = "abcdefghijklmnopqrstuvwxyz";
    public  const int MOD = 1000000007;
}

public class PriorityQueue<T> where T : IComparable<T>
{
    public List<T> _item;
    public int Count { get { return _item.Count; } }
    public bool IsMaxHeap { get; set; }
    public T Peek { get { return _item[0]; } }
    public PriorityQueue(bool IsMaxHeap = true) { _item = new List<T>(); this.IsMaxHeap = IsMaxHeap; }
    private int Compare(int i, int j) => (IsMaxHeap ? 1 : -1) * _item[i].CompareTo(_item[j]);
    private int Parent(int i)
        => (i - 1) >> 1;
    private int Left(int i)
        => (i << 1) + 1;
    public T Enqueue(T val)
    {
        int i = _item.Count;
        _item.Add(val);
        while (i > 0)
        {
            int p = Parent(i);
            if (Compare(i, p) > 0)
            {
                var tmp = _item[i];
                _item[i] = _item[p];
                _item[p] = tmp;
            }
            i = p;
        }
        return val;
    }
    public T Dequeue()
    {
        T val = _item[0];
        _item[0] = _item[_item.Count-1];
        _item.RemoveAt(_item.Count - 1);
        for (int i = 0, j; (j = Left(i)) < _item.Count; i = j)
        {
            if (j != _item.Count - 1 && Compare(j, j + 1) < 0) j++;
            if (Compare(i, j) < 0)
            {
                var tmp = _item[i];
                _item[i] = _item[j];
                _item[j] = tmp;
            }
        }
        return val;
    }
}

public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1 { get; set; }
    public T2 v2 { get; set; }
    public Pair() : this(default(T1), default(T2)) { }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1;this.v2 = v2; }

    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public static Pair<T1, T2> MakePair()
    {
        var r = ReadLine().Split(' ');
        return new Pair<T1, T2>(Input.getValue<T1>(r[0]), Input.getValue<T2>(r[1]));
    }
    public override string ToString()
        => $"{v1.ToString()} {v2.ToString()}";
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3 { get; set; }
    public Pair() : base() { v3 = default(T3); }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1,v2)
    { this.v3 = v3; }
    
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public new static Pair<T1, T2, T3> MakePair()
    {
        var r = ReadLine().Split(' ');
        return new Pair<T1, T2, T3>(Input.getValue<T1>(r[0]), Input.getValue<T2>(r[1]), Input.getValue<T3>(r[2]));
    }
    public override string ToString()
        => $"{base.ToString()} {v3.ToString()}";
}
public class ShortestPath
{
    public static long[] Dijkstra(IList<IEnumerable<Pair<long,int>>> edges,int st)
    {
        var dist = Enumerable.Repeat(long.MaxValue, edges.Count).ToArray();
        var pq = new PriorityQueue<Pair<long, int>>(false);
        pq.Enqueue(new Pair<long, int>(0, st));
        dist[st] = 0;
        while (pq.Count != 0)
        {
            var p = pq.Dequeue();
            if (dist[p.v2] < p.v1) continue;
            foreach (var e in edges[p.v2])
                if (dist[e.v2] > e.v1 + dist[p.v2])
                {
                    dist[e.v2] = e.v1 + dist[p.v2];
                    pq.Enqueue(new Pair<long, int>(dist[e.v2], e.v2));
                }
        }
        return dist;
    }

    public static long[][] WarshallFloyd(int num, IEnumerable<Pair<long, int, int>> edges, bool directed = false)
    {
        var dist = Enumerable.Repeat(0, num).Select(_ => Enumerable.Repeat(long.MaxValue / 2, num).ToArray()).ToArray();
        foreach (var e in edges)
        {
            dist[e.v2][e.v3] = e.v1;
            if (!directed)
                dist[e.v3][e.v2] = e.v1;
        }
        for (var k = 0; k < num; k++)
            for (var i = 0; i < num; i++)
                for (var j = 0; j < num; j++)
                    dist[i][j] = Min(dist[i][j], dist[i][k] + dist[k][j]);
        return dist;
    }

    public static bool BellmanFord(int num,IEnumerable<Pair<long, int, int>> edges, int st, out long[] dist)
    {
        dist = Enumerable.Repeat(long.MaxValue, num).ToArray();
        dist[st] = 0;
        for (var i = 0; i < num - 1; i++)
            foreach (var e in edges)
                if(dist[e.v2]!=long.MaxValue)
                dist[e.v3] = Min(dist[e.v3], dist[e.v2] + e.v1);
        foreach (var e in edges)
        {
            if (dist[e.v2] == long.MaxValue) continue;
            if (dist[e.v3] > dist[e.v2] + e.v1)
                return false;
        }
        return true;
    }
}