hdu 3986 Harry Potter and the Final Battle spfa变形

#include<stdio.h>
#include<string.h>
#include<queue>
#include<vector>
using namespace std;
const int N=1024;
const int inf=0x7fffffff;

struct Edge
{
    int u,v,w,use,del;
};

vector<Edge>edge;
vector<int>G[N];
int n,m,dist[N],inq[N],mp[N][N],path[N],d[N];

void spfa()
{
    int i,u,v;
    memset(inq,0,sizeof(inq));
    memset(mp,0,sizeof(mp));
    for(i=1;i<=n;i++)
    {
        dist[i]=inf;
        path[i]=1;
    }
    dist[1]=0;
    queue<int>q;
    q.push(1);
    inq[1]=1;
    while(!q.empty())
    {
        u=q.front();
        q.pop();
        inq[u]=0;
        for(i=0;i<G[u].size();i++)
        {
            int t=G[u][i];
            if(edge[t].del) continue;
            if(u==edge[t].u) v=edge[t].v;
            else v=edge[t].u;
            if(dist[v]>dist[u]+edge[t].w)
            {
                dist[v]=dist[u]+edge[t].w;
                mp[u][v]=t;path[v]=u;
                if(inq[v]==0)
                {
                    q.push(v);
                    inq[v]=1;
                }
            }
        }
    }
}

int main()
{
    int _,i,j,u,v,w;
    Edge tp;
    scanf("%d",&_);
    while(_--)
    {
        edge.clear();
        for(i=0; i<1024; i++) G[i].clear();
        scanf("%d",&n);
        scanf("%d",&m);
        for(i=0; i<m; i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            tp.u=u,tp.v=v,tp.w=w,tp.use=0,tp.del=0;
            edge.push_back(tp);
            G[u].push_back(i);
            G[v].push_back(i);
        }
        spfa();
        if(dist[n]==inf)
            {printf("-1
");continue;}
        int k1=n,k2=path[n];
        while(1)
        {
            edge[mp[k2][k1]].use=1;
            if(k2==1) break;
            k1=k2;
            k2=path[k2];
        }
        int ans=-1;

       for(i=0; i<m; i++)
        {
            if(edge[i].use)
            {
                edge[i].del=1;
                spfa();
                if(dist[n]==inf)
                {
                    ans=-1;break;
                }
                ans=max(ans,dist[n]);
                edge[i].del=0;
            }
        }
            printf("%d
",ans);
    }
    return 0;
}

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