link cut tree模板（LCT模板）

　　update：2017.09.26

 #include <bits/stdc++.h>
 
 using namespace std;
 
 struct Link_Cut_Tree
 {
     static const int MAXN =  + ;
 
     int ch[MAXN][], fa[MAXN], rev[MAXN], sz[MAXN];
     int sk[MAXN];
 
     bool isroot(int x)
     {
         return ch[fa[x]][] != x && ch[fa[x]][] != x;
     }
 
     void reverse(int x)
     {
         rev[x] ^= , swap(ch[x][],ch[x][]);
     }
 
     void update(int x)
     {
         sz[x] = sz[ch[x][]] +  sz[ch[x][]] +;
     }
 
     void push_down(int x)
     {
         if(!rev[x]) return ;
         if(ch[x][]) reverse(ch[x][]);
         if(ch[x][]) reverse(ch[x][]);
         rev[x]=;
     }
 
     void rotate(int x)
     {
         int f = fa[x], gf = fa[f];
         int t1 = ( x != ch[f][]), t2 = ( f != ch[gf][]), tmp = ch[x][^t1];
         if(!isroot(f)) ch[gf][^t2] = x;
         fa[tmp] = f, fa[x] = gf, ch[x][^t1] = f, fa[f] = x, ch[f][^t1] = tmp;
         update(f);
     }
 
     void splay(int x)
     {
         int top = ;
         sk[++top] = x;
         for(int i = x; !isroot(i); i = fa[i])   sk[++top] = fa[i];
         while(top)  push_down(sk[top--]);
         for(int f = fa[x], gf = fa[f]; !isroot(x); rotate(x), f = fa[x],gf = fa[f])
         if(!isroot(f))
             rotate((x==ch[f][]) ^ (f==ch[gf][]) ? x : f);
         update(x);
     }
 
     void access(int x)
     {
         for(int p = ; x; p = x, x = fa[x])
             splay(x), ch[x][] = p, update(x);
     }
 
     void makeroot(int x)
     {
         access(x), splay(x), reverse(x);
     }
 
     int findroot(int x)
     {
         access(x), splay(x);
         while(ch[x][]) x = ch[x][];
         return x;
     }
     void link(int x,int y)
     {
         makeroot(x), fa[x] = y;
     }
 
     void cut(int x,int y)
     {
         makeroot(x), access(y), splay(y);
         if(ch[y][] == x)   ch[y][] = fa[x] = ;
         update(y);
     }
 
     void debug(void)
     {
         for(int i=;i<=;i++)
             printf("%d %d %d %d %d %d %d\n",i,fa[i],ch[i][],ch[i][],rev[i],sz[i]);
     }
 }lct;
 
 int main(void)
 {
 
     return ;
 }