Zoj 1476 Weird Clock (Tangled water problem)

Meaning

There is a strange clock only minutes of the pointer, a start to stop at the S branch, and then now have D-type coins, put into the clock will be d*s step, asked to need a few such coins.

Analysis:

The topic is not difficult, read understand should know is the use of the mark, because it is not difficult, I started without looking at the topic on the brush to write well, submitted WA, look at the topic to find is to ask a few coins can make the pointer back to 0. Then it was a tragedy to use a 1~1000 loop (which is the range of D >_<) so it's a tangled one.

Because the journey is the same, so when a certain point is repeated after the impossible to come out.

#include <stdio.h>
#include <string.h>
int main ()
{
	int s,d,i,sum;// This is limited to the scope of d rather than the scope of NUM, the title of the second interpretation of the wrong, not because the topic is simple and not carefully read the question.
	int flag[60];//The correct procedure is to mark each seat if it appears a second time, then repeat it, it is impossible to achieve 0 while
	(scanf ("%d%d", &s,&d)!=eof)
	{
		sum= s;
		i=0;
		if (s==0&&d==0) break;
		memset (flag,0,sizeof (flag));
		while (1)
		{
			s= (s+s*d)%60;
			i++;
			flag[s]++;
			if (s==0) break;
			if (flag[s]==2) break;
		if (s==0) printf ("%d\n", I);
		else printf ("impossible\n");
	}
	return 0;
}