Project Euler problem 56, in C (to compare against G-Pascal)

p56.c

// Project Euler problem 56, in C (to compare against G-Pascal)
#include <stdio.h>

#define DIGITS 200

unsigned char a[DIGITS];
unsigned char m[DIGITS];
unsigned char m2[DIGITS];

void numclear(unsigned char *n) {
    unsigned char i;
    for (i = 0; i < DIGITS; i++) {
        n[i] = 0;
    }
}

void numacc(unsigned char* n, unsigned char i, unsigned char carry) {
    for (; carry > 0; i++) {
        carry += n[i];
        n[i] = carry % 10;
        carry /= 10;
    }
}

void nummult(unsigned char *a, unsigned char* b, unsigned char *r) {
    unsigned char i, j;
    numclear(r);
    for (i = 0; i < 2; i++) {
        if (a[i] > 0) {
            for (j = 0; j < DIGITS; j++) {
                if (b[j] > 0) {
                    numacc(r, i + j, a[i] * b[j]);
                }
            }
        }
    }
}

int numsum(unsigned char *n) {
    int result = 0;
    unsigned char i;
    for (i = 0; i < DIGITS; i++) {
        result += n[i];
    }
    return result;
}

int findbest(unsigned char max) {
    unsigned char *pa = &a[0];
    unsigned char *pm = &m[0];
    unsigned char *pm2 = &m2[0];
    unsigned char *tmp;
    int best = 0;
    int current;
    unsigned char i, j;

    numclear(a);
    numacc(pa, 0, 1);

    for (i = 2; i <= max; i++) {
        numacc(pa, 0, 1);
        numclear(pm);
        numacc(pm, 0, 1);

        for (j = 1; j <= max; j++) {
            nummult(pa, pm, pm2);
            tmp = pm2;
            pm2 = pm;
            pm = tmp;

            current = numsum(pm);
            printf("%d^%d:%d ", i, j, current);
            if (current > best) {
                best = current;
            }
        }
    }

    return best;
}

int main() {
    printf("\n%d\n", findbest(99));
    return 0;
}