差分约束系统

#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
#define N 1010
#define M 100010
struct graph{
	int tot,head[M];
	struct edge{
		int next;
		int to,dis;
	}ed[M];
	void addEdge(int from,int to,int dis){
		ed[++tot].next=head[from];
		ed[tot].to=to,ed[tot].dis=dis;
		head[from]=tot;
	}
	void init(){
		tot=0;
		memset(ed,-1,sizeof(ed));
		memset(head,-1,sizeof(head));
	}
}l;
queue<int>q;
int d[N],cntTimes[N];
bool vis[N];
int n,m1,m2,x,y,w;
int spfa(){
	memset(d,0x7f,sizeof(d));
	q.push(1);
	d[1]=0;
	while(!q.empty()){
		int v=q.front();
		q.pop();
		vis[v]=0,cntTimes[v]++;
		for(int i=l.head[v];i;i=l.ed[i].next){
			int u=l.ed[i].to,dis=l.ed[i].dis;
			if(d[v]+dis<d[u]){
				d[u]=d[v]+dis;
				if(!vis[u]){
					q.push(u);
					if(cntTimes[u]>n-1)return -1;
					vis[u]=1;
				}
			}
		}
	}
	if(d[n]>2e8)return -2;
	return d[n];
}
int main(){
	cin>>n>>m1>>m2;
	for(int i=1;i<=m1;i++){
		cin>>x>>y>>w;
		l.addEdge(x,y,w);
	}
	for(int i=1;i<=m2;i++){
		cin>>x>>y>>w;
		l.addEdge(y,x,-w);
	}
	for(int i=1;i<n;i++)l.addEdge(i+1,i,0);
	cout<<spfa();
	return 0;
}