bzoj2049

题解：

加边，减去一条边还是标准的

其他的就暴力好了

代码：

#include<bits/stdc++.h>
using namespace std;
const int N=400005;
char op[10];
int c[N][2],size[N],n,m,y,rev[N],x,t,next[N],fa[N];
int isroot(int x){return c[fa[x]][0]!=x&&c[fa[x]][1]!=x;}
void pushup(int x){size[x]=size[c[x][0]]+size[c[x][1]]+1;}
void pushdown(int x)
{
    if (rev[x])
     {
         rev[x]^=1;rev[c[x][0]]^=1;rev[c[x][1]]^=1;
         swap(c[x][0],c[x][1]);
     }
}
void down(int x)
{
    if (!isroot(x))down(fa[x]);
    pushdown(x);
}
void rotate(int x)
{
    int y=fa[x],z=fa[y],l=c[y][1]==x,r=l^1;
    if(!isroot(y))c[z][c[z][1]==y] = x;
    fa[x]=z;fa[y]=x;fa[c[x][r]]=y;
    c[y][l]=c[x][r];c[x][r]=y;
    pushup(y);pushup(x);
}
void splay(int x)
{
    down(x);
    for (int y=fa[x];!isroot(x);rotate(x),y=fa[x])
     if (!isroot(y))rotate((c[y][0]==x)==(c[fa[y]][0]==y)?y:x);
}
void access(int x)
{
    int t=0;
    while(x)
     {
        splay(x);
        c[x][1]=t;
        t=x;x=fa[x];
     }
}
int find(int x)
{
    for (;fa[x];x=fa[x]);
    return x;
}
void rever(int x){access(x);splay(x);rev[x]^=1;}
void cut(int x,int y){rever(x);access(y);splay(y);c[y][0]=fa[x]=0;}
void link(int x,int y){rever(x);fa[x]=y;splay(x);}
int main()
{
    scanf("%d%d",&n,&m);
    while (m--)
     {
         scanf("%s%d%d",&op,&x,&y);
         if (op[0]=='D')cut(x,y);
         if (op[0]=='C')link(x,y);
         if (op[0]=='Q')
          {
              rever(x);
              if (find(y)==x)puts("Yes");
              else puts("No");
          }
     } 
}