拓撲排序

拓撲排序

以入度爲0的做起點
vector<int> top_sort(){
priority_queue<int ,vector<int> ,greater<int > >Q;
for(int i=1;i<=n;i++){
    if(!indeg[i]){
        Q.push(i);
    }
}
std::vector<int> TOP;
while(!Q.empty()){
    int T=Q.top();
    Q.pop();
    indeg[T]=-1;
    TOP.push_back(T);
    for(auto &e:graph[T]){
        indeg[e]--;
        if(indeg[e]==0)Q.push(e);
    }
}return TOP;
}
}