pku2657.cpp

这是ACM 方面的资料 是PKU的 北京大学的出来的

#include <stdio.h>
int N, Z, M, K;
int st[1001];

int main()
{
	int i, o, s, found, j;

	while (scanf("%d%d%d", &N, &Z, &M) != -1)
	{
		Z--;
		memset(st, 0, sizeof(st));

		for (i = 0; i < M; i++)
		{
			scanf("%d", &o);
			st[o - 1] = 1;
		}
		found = 0;
		for (i = 1; found == 0; i++)
		{
			for (j = 0, s = 0; j <= N; j++)
			{
				s = (s + i) % N;
				if (s == Z)
				{
					found = 1;
					printf("%d\n", i);
					j = N;
					break;
				}
				if (st[s] == 1)
				{
					break;
				}
			}
		}
	}
	return 0;
}