UVA 247

互相可以打电话是一个传递关系，所以Floyd求传递封包，dfs找一个尽量大的圈。

#include<bits/stdc++.h>
using namespace std;

const int maxn = 25;
map<string,int> mp;
map<string,int>::iterator it;
vector<string> names;

bool d[maxn][maxn];
int ID(const string& s)
{
    if((it = mp.find(s))!=mp.end()) return it->second;
    mp.insert(make_pair(s,names.size()));
    names.push_back(s);
    return names.size()-1;
}
bool vis[maxn];
int n,m;

void dfs(int u)
{
    vis[u] = true;
    for(int i = 0; i < n; i++){
        if(!vis[i] && d[u][i] && d[i][u]){
            printf(", %s",names[i].c_str());
            dfs(i);
        }
    }
}

int main()
{
    //freopen("in.txt","r",stdin);
    char s1[50],s2[50];
    int kas = 0;
    while(scanf("%d%d",&n,&m),n){
        if(kas) putchar('
');
        memset(d,0,sizeof(d));
        names.clear(); mp.clear();
        while(m--) {
            scanf("%s%s",s1,s2);
            d[ID(s1)][ID(s2)] = true;
        }

        for(int i = 0; i < n; i++) d[i][i] = true;
        for(int k = 0; k < n; k++)
        for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++){
            d[i][j] |= d[i][k]&&d[k][j];
        }
        printf("Calling circles for data set %d:
",++kas);
        fill(vis,vis+n,0);
        for(int i = 0; i < n; i++){
            if(!vis[i]){
                printf("%s",names[i].c_str());
                dfs(i);
                putchar('
');
            }
        }
    }
    return 0;
}