每加一個新結點，更新一下對各公司控制值,遞歸地加入新控制的結點即可。用一個布爾向量記錄一下已經控制的公司，以免無窮遞歸。
#include?<iostream>
#include?<fstream>
using?namespace?std;
ifstream?fin("concom.in");
ofstream?fout("concom.out");
#ifdef?_DEBUG
#define?out?cout
#define?in?cin
#else
#define?out?fout
#define?in?fin
#endif
int?stock[101][101];
int?n;
bool?control[101];
void?add_control(int?cr,int?ce)
{
????if(control[ce])?return;
????control[ce]?=?true;
????for(int?i?=?1;?i<=100;?++i){
????????if(i!=cr&&!control[i]){
????????????stock[cr][i]+=stock[ce][i];
????????????if(stock[cr][i]>50)
????????????????add_control(cr,i);
????????}
????}
}
void?solve()
{
????memset(stock,0,sizeof(stock));
????
????in>>n;
????int?i,j,p;
????while(n--){
????????in>>i>>j>>p;
????????stock[i][j]?=?p;
????}
????
???for(int?i=1;i<=100;++i){
???????memset(control,0,sizeof(control));
???????for(int?j=1;j<=100;++j){
???????????if(i==j)?continue;
???????????if(?stock[i][j]>50){
???????????????add_control(i,j);
???????????}
???????}
???????for(int?j=1;j<=100;++j){
???????????if(control[j]){
???????????????out<<i<<'?'<<j<<endl;
???????????}
???????}
???}?
}
int?main(int?argc,char?*argv[])
{
????solve();?
????return?0;
}