bzoj 2002 LinkCutTree

我的第一道LCT题（居然1A，O(∩_∩)O哈哈~）

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=2002

大概题意：

给一颗有根树，维护每个节点的深度（到根节点的边数），支持断开子树并把它连接到任意节点。

题解：

Link Cut Tree

 /**************************************************************
     Problem: 2002
     User: idy002
     Language: C++
     Result: Accepted
     Time:1644 ms
     Memory:5984 kb
 ****************************************************************/

 #include <cstdio>
 #include <iostream>
 #define maxn 200010
 using namespace std;

 struct LCT {
     int pre[maxn], son[maxn][], siz[maxn];
     int pnt[maxn];

     void init( int n ) {
         for( int i=; i<=n; i++ ) {
             int nd = i;
             pre[nd] = son[nd][] = son[nd][] = ;
             pnt[nd] = ;
             siz[nd] = ;
         }
     }
     void update( int nd ) {
         siz[nd] = siz[son[nd][]]+siz[son[nd][]]+;
     }
     void rotate( int nd, int d ) {
         int p = pre[nd];
         int s = son[nd][!d];
         int ss = son[s][d];

         son[nd][!d] = ss;
         son[s][d] = nd;
         if( p ) son[p][ nd==son[p][] ] = s;

         pre[nd] = s;
         pre[s] = p;
         if( ss ) pre[ss] = nd;

         if( pnt[nd] ) {
             pnt[s] = pnt[nd];
             pnt[nd] = ;
         }

         update( nd );
         update( s );
     }
     void splay( int nd, int top ) {
         while( pre[nd]!=top ) {
             int p = pre[nd];
             int nl = nd==son[p][];
             if( pre[p]==top ) {
                 rotate( p, nl );
             } else {
                 int pp = pre[p];
                 int pl = p==son[pp][];
                 if( nl==pl ) {
                     rotate( pp, pl );
                     rotate( p, nl );
                 } else {
                     rotate( p, nl );
                     rotate( pp, pl );
                 }
             }
         }
     }
     void cut( int fa ) {
         int s = son[fa][];
         if( s ) {
             son[fa][] = ;
             pre[s] = ;
             pnt[s] = fa;
         }
     }
     void con( int sn ) {
         int fa = pnt[sn];
         pnt[sn] = ;
         son[fa][] = sn;
         pre[sn] = fa;
     }
     void access( int nd ) {
         splay( nd,  );
         cut( nd );
         while( pnt[nd] ) {
             splay( pnt[nd],  );
             cut(pnt[nd]);
             con(nd);
             splay( nd,  );
         }
     }
     void cuttree( int nd ) {
         access( nd );
         pre[ son[nd][] ] = ;
         son[nd][] = ;
     }
     void contree( int nd, int fa ) {
         access( nd );
         pnt[nd] = fa;
         access( nd );
     }
     int getdeep( int nd ) {
         access( nd );
         return siz[son[nd][]];
     }
 };

 int n, m;
 int a[maxn];
 LCT LT;
 int main() {
     scanf( "%d", &n );
     LT.init(n+);
     for( int i=,w; i<=n; i++ ) {
         scanf( "%d", &w );
         int fa = min( i+w, n+ );
         LT.contree( i, fa );
     }
     scanf( "%d", &m );
     for( int i=,opt,x,y; i<=m; i++ ) {
         scanf( "%d", &opt );
         if( opt== ) {  //  query
             scanf( "%d", &x );
             x++;
             printf( "%d\n", LT.getdeep( x ) );
         } else {
             scanf( "%d%d", &x, &y );
             x++;
             int oldf = min( x+a[x], n+ );
             int newf = min( x+y, n+ );
             if( oldf==newf ) continue;
             a[x] = y;
             LT.cuttree( x );
             LT.contree( x, newf );
         }
     }
 }