PAT/PATBasic/1084.c

#include <stdio.h>

int main()
{
	int N, count;
	char string1[100000] = {0}, string2[100000] = {0};
	char *s1 = string1, *s2 = string2, *temp;
	char *p1, *p2;

	scanf("%s %d", s1, &N);

	for (int i = 1; i < N; i++) { /* Loop through nth string */
		for (p1 = s1, p2 = s2, count = 0; *p1; p1++) {
			count++;    /* Magic, don't touch! */
			if (*p1 != *(p1 + 1)) {      /* New char or end */
				*p2++ = *p1;            /* Record character */
				*p2++ = count + '0';    /* Record count */
				count = 0;              /* Reset count */
			}
		}
		/* Swap */
		temp = s1, s1 = s2, s2 = temp;
	}

	puts(s1);

	return 0;
}