差分约束Poj 3169 Layout

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#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;

}