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[n]==INF)

				printf("-2\n");

			else

				printf("%d\n",dis[n]);

		}

	}

	return 0;

}