poj2139 Six Degrees of Cowvin Bacon(Flyod)

Six Degrees of Cowvin Bacon

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 3155 Accepted: 1464

Description

The cows have been making movies lately, so they are ready to play a variant of the famous game "Six Degrees of Kevin Bacon". 

The game works like this: each cow is considered to be zero degrees of separation (degrees) away from herself. If two distinct cows have been in a movie together, each is considered to be one 'degree' away from the other. If a two cows have never worked together but have both worked with a third cow, they are considered to be two 'degrees' away from each other (counted as: one degree to the cow they've worked with and one more to the other cow). This scales to the general case. 

The N (2 <= N <= 300) cows are interested in figuring out which cow has the smallest average degree of separation from all the other cows. excluding herself of course. The cows have made M (1 <= M <= 10000) movies and it is guaranteed that some relationship path exists between every pair of cows. 

Input

* Line 1: Two space-separated integers: N and M 

* Lines 2..M+1: Each input line contains a set of two or more space-separated integers that describes the cows appearing in a single movie. The first integer is the number of cows participating in the described movie, (e.g., Mi); the subsequent Mi integers tell which cows were. 

Output

* Line 1: A single integer that is 100 times the shortest mean degree of separation of any of the cows. 

Sample Input

4 23 1 2 32 3 4

Sample Output

100

Hint

[Cow 3 has worked with all the other cows and thus has degrees of separation: 1, 1, and 1 -- a mean of 1.00 .] 

Source

USACO 2003 March Orange

/*注意不要把0给初始化掉。。无语加油！！！Time:2014-12-6 19:06*/#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int INF=1<<20;const int MAX=300+10;int n,m;int data[MAX];int map[MAX][MAX];void Init(){memset(data,0,sizeof(data));for(int i=1;i<=n;i++){//注意，不要把0初始化掉。。。。。 for(int j=i;j<=n;j++){if(i==j)map[i][j]=0;elsemap[i][j]=map[j][i]=INF;}}}void Floyd(int n){for(int k=1;k<=n;k++){for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){if(map[i][j]>map[i][k]+map[k][j])map[i][j]=map[j][i]=map[i][k]+map[k][j];}}}}int main(){int num;while(scanf("%d%d",&n,&m)!=EOF){Init();while(m--){scanf("%d",&num);for(int i=0;i<num;i++){scanf("%d",&data[i]);for(int j=0;j<i;j++){map[data[j]][data[i]]=map[data[i]][data[j]]=100;}}}Floyd(n);int minV=INF;for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){map[i][0]+=map[i][j];}if(minV>map[i][0])minV=map[i][0];}printf("%d\n",minV/(n-1));}return 0;}