bzoj 3376 [Usaco2004 Open]Cube Stacking 方块游戏——带偏移量的并查集

题目：https://www.lydsy.com/JudgeOnline/problem.php?id=3376

带偏移量的并查集。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=3e4+5,M=1e5+5;
int n,m,x[M],y[M],fa[N],dis[N],siz[N];
char op[M];
int rdn()
{
  int ret=0;bool fx=1;char ch=getchar();
  while(ch>'9'||ch<'0'){if(ch=='-')fx=0;ch=getchar();}
  while(ch>='0'&&ch<='9') ret=(ret<<3)+(ret<<1)+ch-'0',ch=getchar();
  return fx?ret:-ret;
}
int g[20];
void wrt(int x)
{
  if(x<0)putchar('-'),x=-x;
  if(!x)putchar('0');
  int t=0;
  while(x)g[++t]=x%10,x/=10;
  while(t)putchar(g[t]+'0'),t--;
  puts("");
}
int find(int a)
{
  if(fa[a]==a)return a;
  int x=find(fa[a]);
  dis[a]+=dis[fa[a]]; return fa[a]=x;
}
int main()
{
  m=rdn();
  for(int i=1;i<=m;i++)
    {
      op[i]=getchar();
      while(op[i]!='C'&&op[i]!='M')op[i]=getchar();
      x[i]=rdn(); n=max(n,x[i]);
      if(op[i]=='M')y[i]=rdn(),n=max(n,y[i]);
    }
  for(int i=1;i<=n;i++)fa[i]=i,siz[i]=1;
  for(int i=1;i<=m;i++)
    {
      if(op[i]=='M')
    {
      int u=find(x[i]),v=find(y[i]);
      dis[v]=siz[u]; fa[v]=u; siz[u]+=siz[v];
    }
      else
    {
      int d=find(x[i]); wrt(siz[d]-1-dis[x[i]]);
    }
    }
  return 0;
}