BZOJ 1086 王室联邦

http://www.lydsy.com/JudgeOnline/problem.php?id=1086

思路:贪心，每次当储存的儿子大于等于B时，分出一个块，这样每次每个块至多为2B，这样剩下的没有被分的块小于B，可以加入任意一个块，都是合法的。

 #include<algorithm>
 #include<cstdio>
 #include<cmath>
 #include<cstring>
 #include<iostream>
 int tot,go[],first[],next[],n,m;
 int top,c[],pd,size[],cap[],belong[],sz;
 int read(){
     char ch=getchar();int t=,f=;
     while (ch<''||ch>''){if (ch=='-') f=-;ch=getchar();}
     while (''<=ch&&ch<=''){t=t*+ch-'';ch=getchar();}
     return t*f;
 }
 void insert(int x,int y){
     tot++;
     go[tot]=y;
     next[tot]=first[x];
     first[x]=tot;
 }
 void add(int x,int y){
     insert(x,y);insert(y,x);
 }
 void dfs(int x,int fa){
     c[++top]=x;
     for (int i=first[x];i;i=next[i]){
         int pur=go[i];
         if (pur==fa) continue;
         dfs(pur,x);
         if (size[x]+size[pur]>=m){
             cap[++sz]=x;size[x]=;
             while (c[top]!=x) belong[c[top--]]=sz;
         }else size[x]+=size[pur];
     }
     size[x]++;
 }
 void find(int x,int fa){
     if (belong[x]) {
         pd=belong[x];
         return;
     }
     for (int i=first[x];i;i=next[i]){
         int pur=go[i];
         if (pur==fa) continue;
         if (!pd) find(pur,x);
     }
 }
 int main(){
     n=read();m=read();
     if (n<m){
         printf("0\n");
         return ;
     }
     if (m==){
         printf("%d\n",n);
         for (int i=;i<=n;i++)
          printf("%d ",i);
         printf("\n");
         for (int i=;i<=n;i++)
          printf("%d ",i);
         printf("\n");
         return ;
     }
     for (int i=;i<n;i++){
         int x=read(),y=read();
         add(x,y);
     }
     dfs(,);
     pd=;
     int cnt=,th;
     for (int i=;i<=n;i++)
      if (!belong[i]) cnt++,th=;
     if (cnt>=m){
         sz++;
         cap[sz]=th;
         for (int i=;i<=n;i++)
          if (!belong[i]) belong[i]=sz;
     }
     for (int i=;i<=n;i++)
       if (!belong[i]){
          if (!pd) find(i,);
          if (pd) belong[i]=pd;
     }
     printf("%d\n",sz);
     for (int i=;i<=n;i++)
      printf("%d ",belong[i]);
     printf("\n");
     for (int i=;i<=sz;i++)
      printf("%d ",cap[i]);
     printf("\n");
 }