很简单的模板题，不多说了

#include
     
      #include
      
       #include
       
        #define INF 0x3f3f3f3f#define MAXN 1000#define ll long longusing namespace std;struct Edge{    int u,v,cost;}edge[MAXN*40];int pre[MAXN],id[MAXN],vis[MAXN];ll in[MAXN]; ll zhuliu(int root,int n,int m){    ll res=0;    while(1){        for(int i=0;i
        
         > N;    for(int tt=1;tt<=N;tt++){        scanf("%d%d",&n,&m);        for(int i=0;i