hdu1595 find the longest of the shortest

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#include <iostream>#include <cstring>#include <string>#include <cstdio>#include <cmath>#include <algorithm>#include <vector>#include <queue>#include <map>#define inf 0x3f3f3f3f#define ll __int64using namespace std;int mp[1010][1010],d[1010],vis[1010],next[1010],n,m,flag,ans;void dij(int s){    int i,j,tmp,p;    memset(vis,0,sizeof vis);    memset(d,0x3f,sizeof d);    d[s]=0;    for(i=1;i<=n;i++)    {        tmp=inf;p=0;        for(j=1;j<=n;j++)        {            if(!vis[j]&&tmp>d[j])            {                tmp=d[j];                p=j;            }        }        if(tmp==inf) return ;        vis[p]=1;        for(j=1;j<=n;j++)        {            if(!vis[j])            {                if(tmp+mp[p][j]<d[j])                {                    d[j]=tmp+mp[p][j];                    if(flag) next[j]=p;                }            }        }    }}int main(){    int i,j,u,v,w,tmp;    while(~scanf("%d%d",&n,&m))    {        for(i=0;i<=n;i++)            for(j=0;j<=n;j++)                if(i!=j) mp[i][j]=inf;                else mp[i][j]=0;        for(i=0;i<m;i++)        {            scanf("%d%d%d",&u,&v,&w);            mp[u][v]=mp[v][u]=min(w,mp[v][u]);        }        flag=1;        memset(next,0,sizeof next);        dij(1);        ans=d[n];flag=0;        for(i=n;i!=1;i=next[i])        {            tmp=mp[i][next[i]];            mp[i][next[i]]=mp[next[i]][i]=inf;            dij(1);            if(d[n]>ans) ans=d[n];            mp[i][next[i]]=mp[next[i]][i]=tmp;        }        printf("%d\n",ans);    }    return 0;}
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