Very Funny But Not Breaking Any Rules :>

#include <stdio.h>

void count(int num, int *zeros, int *ones, int *twos, int *threes, int *fours, int *fives, int *sixes, int *sevens, int *eights, int *nines);
void printTimes(char c, int times);
int largest();

int main() {
    largest();
}

void count(int num, int *zeros, int *ones, int *twos, int *threes, int *fours, int *fives, int *sixes, int *sevens, int *eights, int *nines){
    // Counts the occurances of each digits without an explicit loop
    if (num == 0)
        return;

    int last = num % 10;
    int remain = num / 10;
    printf("Last: %d\n", last);
    if (last == 0) (*zeros)++;
    else if (last == 1) (*ones)++;
    else if (last == 2) (*twos)++;
    else if (last == 3) (*threes)++;
    else if (last == 4) (*fours)++;
    else if (last == 5) (*fives)++;
    else if (last == 6) (*sixes)++;
    else if (last == 7) (*sevens)++;
    else if (last == 8) (*eights)++;
    else (*nines)++;

    count(remain, zeros, ones, twos, threes, fours, fives, sixes, sevens, eights, nines);
}

void printTimes(char c, int times) {
    // Prints char `c` on the same line `times` times
    if (times == 0)
        return;
    printf("%c", c);
    printTimes(c, times-1);
}

int largest(){
    int num;
    int zeros, ones, twos, threes, fours, fives, sixes, sevens, eights, nines;
    zeros = ones = twos = threes = fours = fives = sixes = sevens = eights = nines = 0;

    scanf("%d", &num);

    count(num<0?-num:num, &zeros, &ones, &twos, &threes, &fours, &fives, &sixes, &sevens, &eights, &nines);

    if (num >= 0) {
        printTimes('9', nines);
        printTimes('8', eights);
        printTimes('7', sevens);
        printTimes('6', sixes);
        printTimes('5', fives);
        printTimes('4', fours);
        printTimes('3', threes);
        printTimes('2', twos);
        printTimes('1', ones);
        printTimes('0', zeros);
    }
    else {
        printf("-");
        printTimes('1', ones);
        printTimes('2', twos);
        printTimes('3', threes);
        printTimes('4', fours);
        printTimes('5', fives);
        printTimes('6', sixes);
        printTimes('7', sevens);
        printTimes('8', eights);
        printTimes('9', nines);
    }
    putchar('\n');
}