ZOJ-3166

找经过某些特定点的最小环，floyd一遍就完事了

#include<stdio.h>
#include<string.h>
#include<limits.h>

int main()
{
	int n, m, c, hotel[100], map[101][101];
	while (scanf("%d %d", &n, &c) != EOF)
	{
		int i, j, k, a, b, d;
		for (i = 0; i < c; i++)
			scanf("%d", &hotel[i]);
		memset(map, 0, sizeof(map));
		for (i = 1; i <= n; i++)
			for (j = 1; j <= n; j++)
				map[i][j] = i == j ? 0 : INT_MAX;
		scanf("%d", &m);
		while (m--)
		{
			scanf("%d %d %d", &a, &b, &d);
			map[a][b] = d;
		}
		for (k = 1; k <= n; k++)
			for (i = 1; i <= n; i++)
				for (j = 1; j <= n; j++)
					if (map[i][k] != INT_MAX && map[k][j] != INT_MAX
							&& map[i][k] + map[k][j] < map[i][j])
						map[i][j] = map[i][k] + map[k][j];
		int res = 0, min = INT_MAX;
		for (k = 0; k < c; k++)
		{
			i = hotel[k];
			for (j = 1; j <= n; j++)
				if (i != j && map[i][j] != INT_MAX && map[j][i] != INT_MAX
						&& map[i][j] + map[j][i] < min)
				{
					min = map[i][j] + map[j][i];
					res = i;
				}
		}
		if (res)
			printf("%d\n", res);
		else
			puts("I will nerver go to that city!");
	}
	return 0;
}