BZOJ 1015 并查集+离线倒序

统计块个数写错了调了好久啊，BZOJ1696的弱化版本。

 #include <iostream>
 #include <cstring>
 #include <algorithm>
 #include <cstdio>
 #include <map>
 #define fi first
 #define se second
 #define mp make_pair
 #define pa pair<int,int>
 using namespace std;
 inline void Get_Int(int &x)
 {
     x=;  char ch=getchar(); int f=;
     while (ch<'' || ch>'') {if (ch=='-') f=-; ch=getchar();}
     while (ch>='' && ch<='') {x=x*+ch-''; ch=getchar();} x*=f;
 }
 inline void Put_Int(int x)
 {
     char ch[]; int top=;
     if (x==) ch[++top]='';
     while (x) ch[++top]=x%+'',x/=;
     while (top) putchar(ch[top--]); putchar('\n');
 }

 const int Maxn=;
 int father[Maxn],head[Maxn],Ans[Maxn],res,u[Maxn],cnt,v[Maxn],n,m,Q,Pos[Maxn];
 bool b[Maxn],ret[Maxn];
 struct Edge{int to,next;}edge[Maxn<<];
 int getfather(int x) {if (x==father[x]) return x; return father[x]=getfather(father[x]);}
 inline void Merge(int u,int v) {father[getfather(u)]=getfather(v);}
 inline void Add(int u,int v) {edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
 inline void Build()
 {
     for (int i=;i<=n;i++)
     {
         if (b[i]) continue;
         for (int j=head[i];j!=-;j=edge[j].next) if (!b[edge[j].to]) Merge(i,edge[j].to);
     }
 }

 int main()
 {
     Get_Int(n),Get_Int(m);
     for (int i=;i<=n;i++) father[i]=i;
     memset(head,-,sizeof(head)); cnt=;
     memset(b,false,sizeof(b));
     for (int i=;i<=m;i++) Get_Int(u[i]),Get_Int(v[i]),Add(u[i]+,v[i]+),Add(v[i]+,u[i]+);
     Get_Int(Q);
     for (int i=;i<=Q;i++) Get_Int(Pos[i]),Pos[i]++,b[Pos[i]]=true;
     Build();
     memset(ret,false,sizeof(ret));
     for (int i=;i<=n;i++) ret[getfather(i)]=true;
     int res=; for (int i=;i<=n;i++) if (ret[i]) res++;//写成了ret[getfather[i]]了>_<
     res-=Q;
     for (int i=Q;i>=;i--)
     {
         Ans[i]=res;
         b[Pos[i]]=false;
         for (int j=head[Pos[i]];j!=-;j=edge[j].next)
             if (!b[edge[j].to])
                 if (getfather(Pos[i])!=getfather(edge[j].to)) res--,Merge(Pos[i],edge[j].to);
         res++;
     }
     Ans[]=res;
     for (int i=;i<=Q;i++) Put_Int(Ans[i]);
     return ;

 }

C++