Task: World Cup group stage
C#: using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static System.Console;
using static System.Linq.Enumerable;

namespace WorldCupGroupStage
{
    public static class WorldCupGroupStage
    {
        static int[][] _histogram;

        static WorldCupGroupStage()
        {
            int[] scoring = new[] { 0, 1, 3 };

            _histogram = Repeat<Func<int[]>>(()=>new int[10], 4).Select(f=>f()).ToArray();

            var teamCombos = Range(0, 4).Combinations(2).Select(t2=>t2.ToArray()).ToList();

            foreach (var results in Range(0, 3).CartesianProduct(6))
            {
                var points = new int[4]; 

                foreach (var (result, teams) in results.Zip(teamCombos, (r, t) => (r, t)))
                {
                    points[teams[0]] += scoring[result];
                    points[teams[1]] += scoring[2 - result];
                }

                foreach(var (p,i) in points.OrderByDescending(a => a).Select((p,i)=>(p,i)))
                    _histogram[i][p]++;
            }
        }
      
       
       
       static IEnumerable<IEnumerable<T>> CartesianProduct<T>(this IEnumerable<IEnumerable<T>> seqs) => 
            seqs.Aggregate(Empty<T>().ToSingleton(), (acc, sq) => acc.SelectMany(a => sq.Select(s => a.Append(s))));
        
       static IEnumerable<IEnumerable<T>> CartesianProduct<T>(this IEnumerable<T> seq, int repeat = 1) => 
            Repeat(seq, repeat).CartesianProduct();

       static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> seq) => 
            seq.Aggregate(Empty<T>().ToSingleton(), (a, b) => a.Concat(a.Select(x => x.Append(b))));

       static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> seq, int numItems) => 
            seq.Combinations().Where(s => s.Count() == numItems);

        private static IEnumerable<T> ToSingleton<T>(this T item) { yield return item; }

        static new string ToString()
        {
            var sb = new StringBuilder();

            var range = String.Concat(Range(0, 10).Select(i => $"{i,-3} "));
            sb.AppendLine($"Points      : {range}");

            var u = String.Concat(Repeat("─", 40+13));
            sb.AppendLine($"{u}");

            var places = new[] { "First", "Second", "Third", "Fourth" };
            foreach (var row in _histogram.Select((r, i) => (r, i)))
            {
                sb.Append($"{places[row.i],-6} place: ");
                foreach (var standing in row.r)
                    sb.Append($"{standing,-3} ");
                sb.Append("\n");
            }

            return sb.ToString();
        }

        static void Main(string[] args)
        {
            Write(ToString());
            Read();
        }
    }
}

Java: import java.util.Arrays;
 
public class GroupStage{
    
    static String[] games = {"12", "13", "14", "23", "24", "34"};
    static String results = "000000";

    private static boolean nextResult(){
        if(results.equals("222222")) return false;
        int res = Integer.parseInt(results, 3) + 1;
        results = Integer.toString(res, 3);
        while(results.length() < 6) results = "0" + results;	
        return true;
    }

    public static void main(String[] args){
        int[][] points = new int[4][10]; 		
        do{
            int[] records = {0,0,0,0};
            for(int i = 0; i < 6; i++){
                switch(results.charAt(i)){
                    case '2': records[games[i].charAt(0) - '1'] += 3; break;    
                    case '1':                                                   
                        records[games[i].charAt(0) - '1']++;
                        records[games[i].charAt(1) - '1']++;
                        break;
                    case '0': records[games[i].charAt(1) - '1'] += 3; break;    
                }
            }
            Arrays.sort(records);	
            points[0][records[0]]++;
            points[1][records[1]]++;
            points[2][records[2]]++;
            points[3][records[3]]++;
        }while(nextResult());
        System.out.println("First place: " + Arrays.toString(points[3]));
        System.out.println("Second place: " + Arrays.toString(points[2]));
        System.out.println("Third place: " + Arrays.toString(points[1]));
        System.out.println("Fourth place: " + Arrays.toString(points[0]));
    }
}