solve.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#define N 100 * 100
bool isDup(char *s1, char *s2)
{
	if (s1 == NULL)
		return s2 == NULL;
	int len1 = strlen(s1), len2 = strlen(s2);
	if (len1 == 0 || len2 == 0)
		return false;
	char *p1, *p2;
	if (len1 >= len2) {
		if (len1 % len2 != 0)
			return false;
		p1 = s1;
		p2 = s2;
	} else {
		if (len2 % len1 != 0)
			return false;
		p1 = s2;
		p2 = s1;
	}
	while (*p1) {
		if (*p1 != *p2)
			return false;
		*p1++, *p2++;
		if (*p2 == 0) {
			if (len1 >= len2)
				p2 = s2;
			else
				p2 = s1;
		}
	}
	return true;
}
int cmp(const void *a, const void *b)
{
	char s1[20], s2[20];
	sprintf(s1, "%d", *(int *)a);
	sprintf(s2, "%d", *(int *)b);
	if (isDup(s1, s2))
		return 0;
	char *p1 = s1, *p2 = s2;
	while (*p1 && p2) {
		if (*p1 != *p2)
			return *p2 - *p1;
		p1++, p2++;
		if (*p1 == 0)
			p1 = s1;
		if (*p2 == 0)
			p2 = s2;
	}
	return 0;
}
char *largestNumber(int *num, int n)
{
	char *result = malloc(sizeof(char) * N);
	memset(result, 0, sizeof(char) * N);
	qsort(num, n, sizeof(num[0]), cmp);
	if (num[0] == 0) {
		strcpy(result, "0\0");
		return result;
	}
	int sum = 0;
	for (int i = 0; i < n; ++i) {
		sum += sprintf(result + sum, "%d", num[i]);
	}
	return result;
}
int main(int argc, char **argv)
{
	int i = 123, j = 456;
	cmp2(&i, &j);
	int a[] = {33, 30, 332, 5, 9};
	int b[] = {0,0,0,0};
	int c[] = {824,938,1399,5607,6973,5703,9609,4398,8247};
	int d[] = {121, 12};
	int e[] = {3,43,48,94,85,33,64,32,63,66};
	printf("%s\n", largestNumber(a, 5));
	printf("%s\n", largestNumber(b, 4));
	printf("%d\n", strcmp(largestNumber(c, 9), "9609938824824769735703560743981399"));
	printf("%s\n", largestNumber(d, 2));
	printf("%s\n", largestNumber(e, 10));
	return 0;
}