差分约束Poj 3169 Layout

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#include <string>
#include <iostream>
using namespace std;
int n;
const int INF=0xfffffff;
struct edge
{
int val;int to;int next;
}e[111111];

int len;int head[11111];

void add(int from,int to,int val)
{
e[len].to=to;e[len].val=val;e[len].next=head[from];head[from]=len++;
}
int dis[11111];
int spfa(int x)
{
int vis[11111];
for(int i=1;i<=n;i++) vis[i]=0;
for(int i=1;i<=n;i++) dis[i]=INF;
vis[x]=1; dis[x]=0;
queue<int> q;
q.push(x);  int cnt[11111]={0}; cnt[x]=1;
while(!q.empty()){
int cur=q.front(); q.pop();vis[cur]=0;
for(int i=head[cur];i!=-1;i=e[i].next){
int cc=e[i].to;
if(dis[cc]>dis[cur]+e[i].val){
dis[cc]=dis[cur]+e[i].val;
if(!vis[cc]){
cnt[cc]++;if(cnt[cc]>n) return 0;
q.push(cc); vis[cc]=1;
}
}
}
}
return 1;
}

int main()
{
int m,l;
while(scanf("%d%d%d",&n,&m,&l)!=EOF){
len=0;memset(head,-1,sizeof(head));
for(int i= 0;i<m;i++){
int a,b,c;scanf("%d%d%d",&a,&b,&c);
if(a>b) {int t=a;a=b;b=t;}
add(a,b,c);
}
for(int i=0;i<l;i++){
int a,b,c;scanf("%d%d%d",&a,&b,&c);
if(a<b){int t=a;a=b;b=t;};
add(a,b,-c);
}
if(!spfa(1)) printf("-1\n");
else{
if(dis
==INF)
printf("-2\n");
else
printf("%d\n",dis
);
}
}
return 0;
}