Task: World Cup group stage
C: #include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int compare(const void *a, const void *b) {
    int int_a = *((int *)a);
    int int_b = *((int *)b);
    return (int_a > int_b) - (int_a < int_b);
}

char results[7];
bool next_result() {
    char *ptr = results + 5;
    int num = 0;
    size_t i;

    
    if (strcmp(results, "222222") == 0) {
        return false;
    }

    
    for (i = 0; results[i] != 0; i++) {
        int d = results[i] - '0';
        num = 3 * num + d;
    }

    
    num++;

    
    while (num > 0) {
        int rem = num % 3;
        num /= 3;
        *ptr-- = rem + '0';
    }
    
    while (ptr > results) {
        *ptr-- = '0';
    }

    return true;
}

char *games[6] = { "12", "13", "14", "23", "24", "34" };
char *places[4] = { "1st", "2nd", "3rd", "4th" };
int main() {
    int points[4][10];
    size_t i, j;

    strcpy(results, "000000");
    for (i = 0; i < 4; i++) {
        for (j = 0; j < 10; j++) {
            points[i][j] = 0;
        }
    }

    do {
        int records[] = { 0, 0, 0, 0 };

        for (i = 0; i < 6; i++) {
            switch (results[i]) {
            case '2':
                records[games[i][0] - '1'] += 3;
                break;
            case '1':
                records[games[i][0] - '1']++;
                records[games[i][1] - '1']++;
                break;
            case '0':
                records[games[i][1] - '1'] += 3;
                break;
            default:
                break;
            }
        }

        qsort(records, 4, sizeof(int), compare);
        for (i = 0; i < 4; i++) {
            points[i][records[i]]++;
        }
    } while (next_result());

    printf("POINTS       0    1    2    3    4    5    6    7    8    9\n");
    printf("-----------------------------------------------------------\n");
    for (i = 0; i < 4; i++) {
        printf("%s place", places[i]);
        for (j = 0; j < 10; j++) {
            printf("%5d", points[3 - i][j]);
        }
        printf("\n");
    }

    return 0;
}

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]));
    }
}