【SPFA】POJ3259-Wormhole

普通的SPFA的负环判定。犯了三个错误，全部写在注释里了。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;
const int MAXNm=10000+500;
const int MAXNn=500+50;
const int INF=0x7fffffff;
int n,m,ww;
int u[MAXNm],v[MAXNm],w[MAXNm];
int first[MAXNn],next[MAXNm];
int dis[MAXNn];
void addedge(int tu,int num)
{
    next[num]=first[tu];
    first[tu]=num;
}

int SPFA()
{
    queue<int> que;
    int vis[MAXNn],appear[MAXNn];
    que.push(0);
    for (int i=0;i<n;i++)
    {
        dis[i]=INF;
        vis[i]=0;
        appear[i]=0;
    }
    /*不要遗漏了上述初始化步骤*/
    dis[0]=0;
    vis[0]=1;
    appear[0]=1;
    
    while (!que.empty())
    {
        int head=que.front();
        que.pop();
        vis[head]=0;
        /*注意这里vis[head]要重归于零！很容易错写成vis[k]=0*/ 
        int k=first[head];
        while (k!=-1)
        {
            if (dis[v[k]]>dis[u[k]]+w[k])
            {
                dis[v[k]]=dis[u[k]]+w[k];
                if (!vis[v[k]])
                /*不要把vis[v[k]]写成vis[k]了*/
                {
                    appear[v[k]]++;
                    vis[v[k]]=1;
                    que.push(v[k]);
                }
                if (appear[v[k]]>=n) return 0;
            }
            k=next[k];
        }
    }
    return 1;
}

int main()
{
    int c;
    scanf("%d",&c);
    for (int kase=0;kase<c;kase++)
    {
        scanf("%d%d%d",&n,&m,&ww);
        for (int i=0;i<n;i++) first[i]=-1;
        
        for (int i=0;i<m;i++)
        {
            scanf("%d%d%d",&u[i],&v[i],&w[i]);
            u[i]--;
            v[i]--;
            addedge(u[i],i);
            u[i+m]=v[i];
            v[i+m]=u[i];
            w[i+m]=w[i];
            addedge(u[i+m],i+m);
        }
        for (int i=2*m;i<2*m+ww;i++)
        {
            scanf("%d%d%d",&u[i],&v[i],&w[i]);
            u[i]--;
            v[i]--;
            w[i]=-w[i];
            addedge(u[i],i);
        }
        if (!SPFA()) cout<<"YES";else cout<<"NO";cout<<endl;
    }
    
    return 0;
}