/*
 * search for a pattern in a string
 * returns the position where the pattern appears
 * if no pattern appears, return -1
 * eg: pattern "BBBA", str "ABBABBBAC" return 4
 */
int search_pattern(char* pattern, char* str) {
	int s_len = 0, p_len = 0, i = 0, j = 0;
	p_len = strlen(pattern);
	s_len = strlen(str);
	while(i < s_len) {
		while(j < p_len && i + j < s_len) {
			/* match each character in the pattern
			 * if any mismatch occurs, the loop will break
			 */
			if(pattern[j] != str[i + j]) break;
			j++;
		}
		/* pattern matched */
		if(j == p_len) return i;

		/* if the pattern didn't match, increase counter in
		 * original string, reset counter in pattern to 0
		 */
		i++;
		j = 0;
	}
	return -1;
}