链接：
https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=183
题意&题解：
紫书P365
代码：
31 int n, m; 32 int d[MAXN][MAXN]; 33 map<string, int> mmp; 34 string s[MAXN]; 35 int par[MAXN]; 36 37 int find(int x) { 38 return par[x] = par[x] == x ? x : find(par[x]); 39 } 40 41 void unite(int x, int y) { 42 int a = find(x), b = find(y); 43 if (a != b) par[a] = b; 44 } 45 46 void init() { 47 mmp.clear(); 48 memset(d, 0, sizeof(d)); 49 } 50 51 int main() { 52 ios::sync_with_stdio(false), cin.tie(0); 53 int cas = 1; 54 while (cin >> n >> m, n) { 55 init(); 56 int cnt = 1; 57 while (m--) { 58 string a, b; 59 cin >> a >> b; 60 if (!mmp[a]) s[cnt] = a, mmp[a] = cnt++; 61 if (!mmp[b]) s[cnt] = b, mmp[b] = cnt++; 62 d[mmp[a]][mmp[b]] = 1; 63 } 64 rep(k, 1, n + 1) rep(i, 1, n + 1) rep(j, 1, n + 1) 65 if (d[i][k] && d[k][j]) d[i][j] = 1; 66 rep(i, 1, n + 1) par[i] = i; 67 rep(i, 1, n + 1) rep(j, 1, n + 1) if (d[i][j] && d[j][i]) unite(i, j); 68 if (cas != 1) cout << endl; 69 cout << "Calling circles for data set " << cas++ << ":" << endl; 70 rep(i, 1, n + 1) if (par[i] == i) { 71 cout << s[i]; 72 rep(j, 1, n + 1) if (par[j] == i && j != i) cout << ", " << s[j]; 73 cout << endl; 74 } 75 } 76 return 0; 77 }