bzoj 2002: [Hnoi2010]Bounce 弹飞绵羊

#include<cstdio>
#include<cmath>


const int N=2000004;
int a[N],where[N],out[N],belong[N],left[500],right[500];
//out记录再走几步出块，where记录出块后到达的点。
int n,m;

inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch>‘9‘||ch<‘0‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}

inline void divide(int x)
{
    for(int i=1;i<=x;i++)
    left[i]=right[i-1]+1,right[i]=i*x;
    right[x]=n;
    for(int i=1;i<=x;i++)
        for(int j=left[i];j<=right[i];j++)
        belong[j]=i;
    for(int i=n;i>=1;i--)
    {
        if(where[i]>right[belong[i]])out[i]=1;
        else out[i]=out[where[i]]+1,where[i]=where[where[i]];
    }
}

inline void query(int x)
{
    int ans=0;
    while(x<=n)
    {
        ans+=out[x],x=where[x];
    }
    printf("%d\n",ans);
}

inline void modify(int x,int y)
{
    int i,j;
    int tmp=belong[x],l=left[tmp],r=right[tmp];
    a[x]=x+y;
    if(a[x]>r)out[x]=1,where[x]=a[x];
    else out[x]=out[a[x]]+1,where[x]=where[a[x]];
    for(i=x-1;i>=l;i--)
    {
        if(a[i]<=x)
        out[i]=out[a[i]]+1,where[i]=where[a[i]];
    }
}

int main()
{
    n=read();
    int x=sqrt(n);
    for(int i=1;i<=n;i++)
    a[i]=read(),where[i]=i+a[i],a[i]=where[i];
    
    divide(x);
    m=read();
    int i,j,k;
    while(m--)
    {
        i=read();
        if(i==1)
        {
            j=read();
            j++;
            query(j);
        }
        else 
        {
            j=read(),k=read();
            j++;
            modify(j,k);
        }
    }
    return 0;
}