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- #include<bits/stdc++.h>
- using namespace std;
- vector<int> v[50009];
- vector<int> vr[50009];
- vector<int> comp[50009];
- set<int> com[50009];
- bool vis[50009];
- int parent[50009];
- int result[50009];
- vector <int> ans;
- vector<int> ans2;
- int scc = 1;
- int n;
- void init(){
- scc = 1;
- ans.clear();
- ans2.clear();
- memset(vis,0,sizeof vis);
- memset(parent,0,sizeof parent);
- memset(result,0,sizeof result);
- for(int i=0;i<=n;i++){
- v[i].clear();
- vr[i].clear();
- comp[i].clear();
- com[i].clear();
- }
- }
- void dfs(int s){
- vis[s] = true;
- for(int i=0;i<v[s].size();i++){
- if(!vis[v[s][i]]){
- dfs(v[s][i]);
- }
- }
- ans.push_back(s);
- }
- void dfs2(int s){
- vis[s] = true;
- parent[s] = scc;
- com[scc].insert(s);
- for(int i=0;i<vr[s].size();i++){
- if(!vis[vr[s][i]]){
- dfs2(vr[s][i]);
- }
- }
- ans2.push_back(s);
- }
- int dfs3(int s){
- vis[s] = true;
- for(int i=0;i<comp[s].size();i++){
- if(!vis[comp[s][i]]){
- result[s] = result[s] + dfs3(comp[s][i]);
- }
- else {
- result[s] =result[s] + result[comp[s][i]];
- }
- }
- return result[s];
- }
- int main (){
- int test;
- int a,b;
- scanf("%d",&test);
- for(int i=0;i<test;i++){
- scanf("%d",&n);
- init();
- for(int j=0;j<n;j++){
- scanf("%d %d",&a,&b);
- v[a].push_back(b);
- vr[b].push_back(a);
- }
- for(int j=1;j<=n;j++){
- if(!vis[j]){
- dfs(j);
- }
- }
- memset(vis,0,sizeof vis);
- reverse(ans.begin(),ans.end());
- for(int j=0;j<ans.size();j++){
- if(!vis[ans[j]]){
- dfs2(ans[j]);
- scc++;
- // for(int k=0;k<ans2.size();k++){
- // cout << ans2[k] << " ";
- // }
- // cout << endl;
- // ans2.clear();
- }
- }
- for(int j=1;j<=n;j++){
- for(int k=0;k<v[j].size();k++){
- if(parent[j]!=parent[v[j][k]]){
- comp[parent[j]].push_back(parent[v[j][k]]);
- }
- }
- }
- for(int j=1;j<scc;j++){
- result[j] = com[j].size();
- }
- memset(vis,false,sizeof vis);
- for(int j=1;j<scc;j++){
- if(!vis[j]){
- dfs3(j);
- }
- }
- int idx = 1;
- int maxx = result[1];
- for(int j=1;j<scc;j++){
- if(result[j]>maxx){
- maxx = result[j];
- idx = j;
- }
- else if(result[j]==maxx){
- if(*com[idx].begin()>*com[j].begin()){
- idx = j;
- }
- }
- }
- printf("Case %d: %d\n",i+1,*com[idx].begin());
- }
- return 0;
- }
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