SkynetTheVirus.cs

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

/**
 * Auto-generated code below aims at helping you parse
 * the standard input according to the problem statement.
 **/
class Player
{
    static void Main(string[] args)
    {
        string[] inputs;
        inputs = Console.ReadLine().Split(' ');
        int N = int.Parse(inputs[0]); // the total number of nodes in the level, including the gateways
        int L = int.Parse(inputs[1]); // the number of links
        int E = int.Parse(inputs[2]); // the number of exit gateways
        Tuple<int, bool>[,] ra = new Tuple<int, bool>[N, N]; //Static Graph  Tuple<int,bool> int = node bool=gateway    1=link 0=nolink
        List<int> ls = new List<int>(); //List of Gateways
        #region Init Graph

        for (int i = 0; i < N; i++)
        {
            for (int j = 0; j < N; j++)
            {
                ra[i, j] = new Tuple<int, bool>(0, false);
            }
        }

        #endregion
        for (int i = 0; i < L; i++)
        {
            inputs = Console.ReadLine().Split(' ');
            int n1 = int.Parse(inputs[0]); // N1 and N2 defines a link between these nodes
            int n2 = int.Parse(inputs[1]);
            ra[n1, n2] = new Tuple<int, bool>(1, false); //create link  n1 -> n2
            ra[n2, n1] = new Tuple<int, bool>(1, false); //create link in both ways n2 -> n1
        }
        for (int i = 0; i < E; i++)
        {
            int G = int.Parse(Console.ReadLine()); // the index of a gateway node
            ls.Add(G);  //add Gate way to my gateway list
            ra[G, G] = new Tuple<int, bool>(ra[G, G].Item1, true); //add gateway in the graph tupple int,bool with bool at true
        }

        // game loop
        while (true)
        {
            int SI = int.Parse(Console.ReadLine()); // The index of the node on which the Skynet agent is positioned this turn
            int rep = isLinkedToGateWay(ra,ls,SI);
            if (rep != -1) //if this node is linked to a Gateway
            {
                string txt = deleteLink(ra, SI, rep);
                Console.WriteLine(txt);
            }
            else
            {
                string txt = isolateGateWay(ra, ls);
                Console.WriteLine(txt);
            }
        }
    }


    //Return -1 if not linked or gatewaynumber if linked to a gateway
    static int isLinkedToGateWay(Tuple<int, bool>[,] ra, List<int> ls, int node)
    {
        int ret = -1;
        bool go = true;
        int N = ra.GetLength(0);
        int k=0,i=0;
        for (k = 0; k < ls.Count && go; k++)
        {
            i = 0;
            while (go && i < N)
            {
                if (ra[i,node].Item1==1)
                {
                    go = i != ls[k]; //is i a gateway ? invert true false
                }
                i += go ? 1 : 0;
            }
        }
        if (!go)
        {
            ret = i;
        }
        return ret;
    }

    //Retrun the link to destroy near the first gateway in the list if there is a Gateway or Emptystring
    static string isolateGateWay(Tuple<int, bool>[,] ra, List<int> ls)
    {
        string ret = String.Empty;
        int N = ra.GetLength(0);
        int node = -1;
        int i = 0;
        if (ls.Count > 0)
        {

            while (i < N && node == -1)
            {
                node = ra[i,ls[0]].Item1!=0 ? i:-1;
                i += node != -1 ? 0 : 1;
            }
        }

        if(node != -1)
        {
            ret = node+" " + ls[0];
            ra[i, ls[0]] = new Tuple<int, bool>(0,false);
            ra[ls[0], i] = new Tuple<int, bool>(0, false);
        }

        return ret;
    }

    //Delete link between skynet and the given gatevay 
    static string deleteLink(Tuple<int, bool>[,] ra, int node, int gateway)
    {
        ra[node,gateway] = new Tuple<int, bool>(0,false);
        ra[gateway,node] = new Tuple<int, bool>(0,false);
        return node+" "+gateway;
    }

}