Parliament coalition

parliament.cs

using System;

namespace Sketch {

public class Parliament {
  public static string[] parties = new string[] {
    "Likud",
    "KahulLaval",
    "JointList",
    "Shas",
    "YahadutHatora",
    "IsrealBeitenu",
    "AvodaGesherMeretz",
    "Yemina", // 8 
  };
  public static int[] seats = new int[] {
    36,
    33,
    15,
    9,
    7,
    7,
    7,
    6,
  };
  public static double[,] likes = new double[,] {
    // likud, 	kahul,	joint, 	shas,	yahdut,	beitenu, avoda,	yemina
    {   1.0,    -0.5,   -1.0,   0.95,   0.95,   -0.2,   -0.8,   0.95}, // likud
    {  -0.9,     1.0,   -0.6,   -0.5,   -0.5,    0.5,    0.8,   -0.2}, // kahul
    {  -0.9,    -0.3,    1.0,   -0.6,   -0.6,   -1.0,   -0.2,   -1.0}, // joint
    {  0.96,    -0.7,   -0.6,    1.0,    0.9,   -1.0,   -0.7,    0.8}, // shas
    {  0.97,    -0.6,   -0.6,   0.92,    1.0,   -1.0,   -0.6,    0.7}, // yahadut
    {  -0.4,    -0.1,   -1.0,  -0.99,  -0.99,    1.0,   -0.6,    0.1}, // beitenu
    { -0.95,    0.98,    0.3,  -0.89,  -0.89,   -0.01,   1.0,  -0.75}, // avoda
    { 0.999,   -0.92,   -1.0,   0.86,   0.85,   -0.3,   -0.4,    1.0}, // yemina
  };


public static void Main() {
  int states=1<<parties.Length; //2^parties.Length

  double bestRank=-1e10;
  int bestState=0;

  /* state is a bit array, 1-party is in coalision, 0-party is in opposition */
  for (int state=1; state<states; state+=1) {
    if (GetSeats(state)<61) continue;

    var rank=GetRank(state);
    if (rank>bestRank) { bestRank=rank; bestState=state; }
    //PrintParties(state, rank);
  }

  if (bestState==0) Console.WriteLine("New election, please!");
  else PrintParties(bestState, bestRank);
}

public static int GetSeats(int state) {
  int ttl=0;
  for (int ix=0; state>0; state=state>>1, ix+=1) {
    if ((state&1)==0) continue;
    ttl+=seats[ix];
  }
  return ttl;
}

public static double GetRank(int state) {
  double rank=0; int ttl=0;
  for (int ix=0; state>0; state=state>>1, ix+=1) {
    if ((state&1)==0) continue;
    ttl+=1;

    /* exclude current party from the state */
    int otherState=state>>1;
    for (int otherIx=ix+1; otherState>0; otherState=otherState>>1, otherIx+=1) {
      if ((otherState&1)==0) continue;

      rank+=likes[ix,otherIx]+likes[otherIx,ix];
    }
  }

  return rank/(0.5*ttl*(ttl-1)); /* normalize by count of parties pairs */
}

public static void PrintParties(int state, double rank) {
  Console.Write("Rank: {0}, Seats: {1}, Parties:", rank, GetSeats(state));
  for (int ix=0; state>0; state=state>>1, ix+=1) {
    if ((state&1)==0) continue;
    Console.Write(" {0}", parties[ix]);
  }
  Console.WriteLine("");
}

}

}

result.txt

Rank: 0.6029, Seats: 65, Parties: Likud Shas YahadutHatora IsrealBeitenu Yemina

https://ayende.com/blog/190275-C/giving-a-job-candidate-a-hard-problem