P1038 [NOIP2003 提高组] 神经网络 ( 拓扑

#include
using namespace std;
using VI = vector<int>;
using ll = long long;
using PII = pair <int , int>;
const int mod = 998244353;
ll n,p;
ll u[110];
ll c[210];
ll out[110];
ll in[110];
vector g[1010];
int main(){
    cin>>n>>p;
    for(int i = 1 ; i <= n ; i++){
        cin>>c[i]>>u[i];
    }
    for(int i = 1 ; i <= p ; i++){
        int a,b,w;
        cin>>a>>b>>w;
        g[a].push_back({b,w});
        in[b]++;
        out[a]++;
 
    }
    queue<int> q;
    for(int i = 1 ; i <= n ; i++){
        if(in[i] == 0) q.push(i);
    }
    while(q.size()){
        auto x = q.front();
        q.pop();
        for(auto v: g[x]){
            c[v.first] += v.second * c[x];
            in[v.first] --;
            if(in[v.first] == 0){
                q.push(v.first);
                c[v.first] = max(0ll , c[v.first] - u[v.first]);
            }
        }
    }
    int flag = 0;
    for(int i = 1 ; i <= n ; i++){
        if(out[i] == 0 && c[i] > 0){
            flag = 1;
            cout<" "<"\n";
        }
    }
    if(flag == 0) cout<<"NULL";
}

小于0的贡献不传递，把小于0的贡献都当作0来计算