紫书 习题 11-1 UVa 821 （Floyd）

水题， Floyd一遍就完了。

#include<cstdio>
#include<algorithm>
#define REP(i, a, b) for(int i = (a); i < (b); i++)
using namespace std;

const int MAXN = 101;
int d[MAXN][MAXN], n;

int main()
{
	int u, v, kase = 0;
	while(~scanf("%d%d", &u, &v) && u && v)
	{
		REP(i, 1, MAXN)
			REP(j, 1, MAXN)
				d[i][j] = (i == j ? 0 : 1e9);
				
		while(1)
		{
			d[u][v] = 1;
			if(!(~scanf("%d%d", &u, &v) && u && v)) break;
		}
		
		REP(k, 1, MAXN)
			REP(i, 1, MAXN)
				REP(j, 1, MAXN)
					d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
		
		int sum = 0, cnt = 0;
		REP(i, 1, MAXN)
			REP(j, 1, MAXN)
				if(d[i][j] != 1e9 && i != j)
				{
					cnt++;
					sum += d[i][j];
				}
		
		printf("Case %d: average length between pages = %.3f clicks\n", ++kase, (double)sum / cnt);
	}
	
	return 0;
}