hdu 5036 Explosion

bitset真是黑科技

#pragma comment(linker, "/STACK:102400000,102400000")
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
#include<bitset>
using namespace std;
#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\len"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\len"
#define in64 "%lld"
#endif
/************ for topcoder by zz1215 *******************/
#define foreach(c,itr)  for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FF(i,a)         for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a,b)      for( int i = (a) ; i >= (b) ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define pb              push_back
#define pf              push_front
#define X               first
#define Y               second
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define MC(a,b)			memcpy(a,b,sizeof(b))
#define MAX(a,b)        ((a)>(b)?(a):(b))
#define MIN(a,b)        ((a)<(b)?(a):(b))
#define read            freopen("out.txt","r",stdin)
#define write           freopen("out2.txt","w",stdout)

const int maxn = 1111;

int n;
bitset<maxn>dp[maxn];

void gao(){
	for (int k = 1; k <= n; k++){
		for (int now = 1; now <= n; now++){
			if (dp[now][k]){
				dp[now] |= dp[k];
			}
		}
	}
}

int main(){
	int T;
	cin >> T;
	for (int tt = 1; tt <= T; tt++){
		cin >> n;
		for (int i = 1; i <= n; i++){
			dp[i].reset();
			dp[i][i] = 1;
		}
		int x, to;
		for (int now = 1; now <= n; now++){
			//cin >> x;
			SS(x);
			for (int i = 1; i <= x; i++){
				//cin >> to;
				SS(to);
				dp[now][to] = 1;
			}
		}
		gao();
		double ans = 0.0;
		int cnt;
		for (int i = 1; i <= n; i++){
			cnt = 0;
			for (int j = 1; j <= n; j++){
				if (dp[j][i]){
					cnt++;
				}
			}
			ans += 1.0 / (double)(cnt);
		}
		printf("Case #%d: %.5lf\n", tt, ans);
	}
	return 0;
}