HDU 1595 find the longest of the shortest

#include <iostream>
#include <cstdio>
#include <memory.h>
#include <functional>
#include <queue>
#include <vector>
using namespace std;
#define pii pair<int,int>
const int maxn=1010;

int g[maxn][maxn],dis[maxn],path[maxn],n,m;
bool vis[maxn];
vector<int>pv;
void printPath(int v){
if(v==-1){
return;
}
printPath(path[v]);
pv.push_back(v);
}
int dijkstra(int s){
priority_queue<pii,vector<pii>,greater<pii> >q;
memset(dis,0X3F,sizeof(dis));
memset(vis,0,sizeof(vis));
memset(path,0,sizeof(path));
dis[s]=0;
path[s]=-1;
q.push(make_pair(0,s));
while (q.size())
{
pii t=q.top();
q.pop();
if(t.second==1)return dis[1];
else if(vis[t.second])continue;
vis[t.second]=1;
for (int i=1;i<=n;++i)
{
if(g[t.second][i]&&dis[i]>dis[t.second]+g[t.second][i]&&!vis[i]){
path[i]=t.second;
dis[i]=dis[t.second]+g[t.second][i];
q.push(make_pair(dis[i],i));
}
}
}
}
int main(){
while (scanf("%d%d",&n,&m)==2)
{
int ans=0;
memset(g,0,sizeof(g));
pv.clear();
for (int i=0;i<m;++i)
{
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
if(g[u][v]==0){
g[u][v]=g[v][u]=w;
}else{
g[u][v]=g[v][u]=min(g[u][v],w);
}
}
dijkstra(n);
printPath(1);
for (int i=0;i<pv.size()-1;++i)
{
int t=g[pv[i]][pv[i+1]];
g[pv[i]][pv[i+1]]=g[pv[i+1]][pv[i]]=0;//删除
ans=max(ans,dijkstra(n));
g[pv[i]][pv[i+1]]=g[pv[i+1]][pv[i]]=t;//还原
}
printf("%d\n",ans);
}
return 0;
}