BZOJ 2002 [Hnoi2010]Bounce 弹飞绵羊

#include<cstdio>
#include<cmath>
#define N 200005
#define SN 1000
using namespace std;
int k
, step
, next
, n, block, cnt, l[SN], r[SN], belong
;
void init()
{
block=sqrt(n);
if(block*block==n)cnt=block;
else cnt=block+1;
l[1]=0; r[1]=block-1;
for(int i = 2; i <= block; i++)
{
l[i]=l[i-1]+block;
r[i]=r[i-1]+block;
}
if(cnt>block)
l[cnt]=l[cnt-1]+block, r[cnt]=n-1;
for(int i = 1; i <= cnt; i++)
{
for(int j = r[i]; j >= l[i]; j--)
{
belong[j]=i;
if(j+k[j]>r[i])step[j]=1, next[j]=j+k[j];
else step[j]=step[j+k[j]]+1, next[j]=next[j+k[j]];
}
}
}
int main()
{
scanf("%d",&n);
for(int i = 0; i < n; i++)
scanf("%d",&k[i]);
init();
int m; scanf("%d",&m);
while(m--)
{
int cmd, x, y;
scanf("%d",&cmd);
if(cmd==1)
{
scanf("%d",&x);
int ans=0;
while(x<n)
{
ans+=step[x];
x=next[x];
}
printf("%d\n",ans);
}
else
{
scanf("%d%d",&x,&y);
k[x]=y;
for(int i = x, ii = l[belong[x]]; i >= ii; i--)
{
if(i+k[i]>r[belong[x]])step[i]=1,next[i]=i+k[i];
else step[i]=step[i+k[i]]+1, next[i]=next[i+k[i]];
}
}
}
}