BZOJ 2002 弹飞绵羊（分块）

 1 #include<iostream>
 2 #include<cmath>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cstdio>
 6 #define db double
 7 using namespace std;
 8 const int N=200005;
 9 int n,m,a[N],t1,t2,t3,siz,s,t,to[N],stp[N];
10 int query(int p){
11     int rt=0;while(~p){
12         rt+=stp[p];p=to[p];
13     } return rt;
14 } void update(int p,int da){
15     s=p/siz*siz;t=(p/siz+1)*siz-1;
16     a[p]=da;for(int i=p;i>=s;i--)
17     if(i+a[i]>=n) to[i]=-1,stp[i]=1;
18     else if(i+a[i]>t) to[i]=i+a[i],stp[i]=1;
19     else to[i]=to[i+a[i]],stp[i]=stp[i+a[i]]+1;
20 } int main(){
21     scanf("%d",&n);siz=(int)sqrt((db)n+0.5);
22     for(int i=0;i<n;i++) scanf("%d",&a[i]);
23     for(int i=n-1;~i;i--){
24         t=(i/siz+1)*siz-1;
25         if(i+a[i]>=n) to[i]=-1,stp[i]=1;
26         else if(i+a[i]>t) 
27         to[i]=i+a[i],stp[i]=1;
28         else to[i]=to[i+a[i]],
29         stp[i]=stp[i+a[i]]+1;
30     } scanf("%d",&m);
31     while(m--){
32         scanf("%d%d",&t1,&t2);
33         if(t1==1) printf("%d\n",query(t2));
34         else scanf("%d",&t3),update(t2,t3);
35     } return 0;
36 }