我写的是LCT,开始的时候修改操作挂了，正确的修改姿势有两种，一种是记录每个点实际的fa是谁，然后修改u的时候access(fa[u])然后splay(u)，然后把u的pre直接指向该指向的点，fa[u]->ch[1]==NULL就可以了；另外一种是access(u)，然后断掉它的左儿子，然后直接接过去。
1 #include <cstdio> 2 #include <iostream> 3 #include <cstdlib> 4 #include <algorithm> 5 #include <cstring> 6 #include <cmath> 7 using namespace std; 8 const int N = 300010; 9 struct SPLAY { 10 SPLAY* ch[2]; 11 SPLAY* pre; 12 int size; 13 SPLAY() { 14 ch[0] = ch[1] = pre = NULL; 15 size = 0; 16 } 17 void update() { 18 size = 1; 19 if(ch[0]!=NULL) size += ch[0]->size; 20 if(ch[1]!=NULL) size += ch[1]->size; 21 } 22 }*dian[N],dizhi[N]; 23 bool is_root(SPLAY* x) { 24 if(x->pre==NULL) return true; 25 if((x->pre->ch[0]==NULL || x->pre->ch[0]!=x) && (x->pre->ch[1]==NULL || x->pre->ch[1]!=x)) return true; 26 return false; 27 } 28 inline void rotate(SPLAY* x,int d) { 29 SPLAY* y = x->pre; 30 y->ch[!d] = x->ch[d]; 31 if(x->ch[d]!=NULL) x->ch[d]->pre = y; 32 x->pre = y->pre; 33 if(!is_root(y)) { 34 if(y==y->pre->ch[d]) y->pre->ch[d] = x; 35 else y->pre->ch[!d] = x; 36 } 37 x->ch[d] = y;y->pre = x; 38 y->update() ; x->update(); 39 } 40 inline void splay(SPLAY* x) { 41 while(!is_root(x)) { 42 SPLAY* y = x->pre; 43 if(x==y->ch[0]) { 44 if(!is_root(y) && y->pre->ch[0]==y) rotate(y,1); 45 rotate(x,1); 46 } else { 47 if(!is_root(y) && y->pre->ch[1]==y) rotate(y,0); 48 rotate(x,0); 49 } 50 } 51 } 52 int n,m,t; 53 inline void access(SPLAY* x) { 54 for(splay(x),x->ch[1] = NULL ; x->pre!=NULL ; splay(x),x->ch[1] = NULL) { 55 splay(x->pre); 56 x->pre->ch[1] = x; 57 } 58 } 59 inline int query(int x) { 60 access(dian[x]); 61 splay(dian[x]); 62 return dian[x]->ch[0]->size; 63 } 64 int fa[N]; 65 inline void modify(int x,int y) { 66 int to = x+y>n?n+1:x+y; 67 access(dian[fa[x]]); 68 splay(dian[x]); 69 dian[x]->pre = dian[to]; 70 fa[x] = to; 71 } 72 int main() { 73 scanf("%d",&n); 74 for(int i = 1 ; i <= n+1 ; ++i) dian[i] = &dizhi[++t]; 75 for(int i = 1 ; i <= n ; ++i) { 76 int x; 77 scanf("%d",&x); 78 if(i+x>n) dian[i]->pre = dian[n+1],fa[i] = n + 1; 79 else dian[i]->pre = dian[i+x],fa[i] = i + x; 80 } 81 scanf("%d",&m); 82 for(int i = 1 ; i <= m ; ++i) { 83 int k,x,y; 84 scanf("%d",&k); 85 if(k==1) { 86 scanf("%d",&x); 87 x++; 88 printf("%d ",query(x)); 89 } else { 90 scanf("%d%d",&x,&y); 91 x++; 92 modify(x,y); 93 } 94 } 95 }