layout布局[差分约束]

​​传送门​​

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#include<bits/stdc++.h>
#define N 1005
#define M 20005*2
#define inf 1e15
#define LL long long
using namespace std;
int n,ml,md,vis[N],times[N]; LL dis[N];
int first[N],next[M],to[M],w[M],tot;
int read(){
  int cnt=0,f=1;char ch=0;
  while(!isdigit(ch)){if(ch=='-') f=-1;ch=getchar();}
  while(isdigit(ch))cnt=cnt*10+(ch-'0'),ch=getchar();
  return cnt*f;
}
void add(int x,int y,int z){
  next[++tot]=first[x],first[x]=tot,to[tot]=y,w[tot]=z;
}
LL spfa(){
  for(int i=1;i<=n;i++) dis[i]=inf;
  queue<int> q;
  q.push(1); dis[1]=0,vis[1]=1;
  while(!q.empty()){
    int x=q.front(); q.pop(); vis[x]=0 , times[x]++;
    if(times[x]>=n) return -1;
    for(int i=first[x];i;i=next[i]){
      int t=to[i]; 
      if(dis[t] > dis[x] + w[i]){
        dis[t] = (LL)dis[x] + w[i]; 
        if(!vis[t]) vis[t]=1 , q.push(t);
      }
    }
  }return dis[n]==inf ? -2 : dis[n];
}
int main(){
  n=read(),ml=read(),md=read();
  while(ml--) {int x=read(),y=read(),z=read(); add(x,y,z);}
  while(md--) {int x=read(),y=read(),z=read(); add(y,x,-z);}
  for(int i=2;i<=n;i++) add(i,i-1,0);
  printf("%lld",spfa()); return 0;
}