SPOJ - UOFTCG 树的最小路径覆盖

 //SPOJ - UOFTCG 树的最小路径覆盖

 #include <bits/stdc++.h>
 #include <vector>
 using namespace std;
 #define ll long long
 const int mod = 1e9+;
 const int maxn=;
 const int N = 1e5+;
 int cnt;
 int head[N];
 struct edge{
     int to,next;
 }e[N<<];
 void addedge(int u,int v){
     e[cnt].to=v,e[cnt].next=head[u],head[u]=cnt++;
     e[cnt].to=u,e[cnt].next=head[v],head[v]=cnt++;
 }

 int cov[N];
 bool vis[N],used[N];
 void dfs(int u,int f){
     used[u]=;
     cov[u]=;
     int tot=;
     for(int i=head[u];~i;i=e[i].next){
         int v=e[i].to;
         if(v==f) continue;
         dfs(v,u);
         cov[u]+=cov[v];
         if(!vis[v]) tot++;
     }
     if(tot>=) cov[u]-=,vis[u]=;
     else if(tot==) cov[u]-=;
 }
 int main(){
     // freopen("in.txt","r",stdin);
     int T;
     scanf("%d",&T);
     while(T--){
         cnt=;
         memset(used,false,sizeof(used));
         memset(head,-,sizeof(head));
         memset(cov,,sizeof(cov));
         memset(vis,false,sizeof(vis));
         int n,m;
         scanf("%d%d",&n,&m);
         for(int i=;i<=m;i++){
             int u,v;
             scanf("%d%d",&u,&v);
             addedge(u,v);
         }
         int ans=;
         for(int i=;i<=n;i++){
            if(!used[i]) dfs(i,),ans+=cov[i];
         }
         // cout<<cov[1]<<endl;
         printf("%d\n",ans+n-);
     }
 }