luogu 1196 银河英雄传说 带权并查集

带权并查集，其实有点像许多队列问情况的小学奥数

#include<bits/stdc++.h>
#define rep(i,x,y) for(register int i=x;i<=y;i++)
using namespace std;
const int N=30050;
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
    while(isdigit(ch)){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}
    return x*f;}
int fa[N],cnt[N],dfn[N],n,m,x,y,xx,yy;char s; 
//dfn代表i和所在队列队头的距离 
inline int aabs(int x){return x>0?x:-x;}
inline int find(int x){
    if(fa[x]==x) return x;
    int ff=find(fa[x]);dfn[x]+=dfn[fa[x]];
    fa[x]=ff;return ff;}
int main(){
        m=read();n=30000;rep(i,1,n) fa[i]=i,dfn[i]=0,cnt[i]=1;
    while(m--){
        cin>>s;x=read();y=read();
        xx=find(x),yy=find(y);
        if(s=='M')
            fa[xx]=yy,dfn[xx]+=cnt[yy],cnt[yy]+=cnt[xx],cnt[xx]=0;
        else if(s=='C')
            if(xx!=yy) printf("-1\n");
            else printf("%d\n",aabs(dfn[x]-dfn[y])-1);    
    }return 0;
}