2002: [Hnoi2010]Bounce 弹飞绵羊 分块/LCT

似乎正解是LCT。。这也是我学LCT做的第一道题。。然而今天写了一发分块看起来已经碾压LCT了。。。

两种都算模板级别的题了，分块更好写一些。

LCT：

#include<iostream>#include<cstdio>#define N 200005using namespace std;int n,m,next[N],tree[N][2],fa[N],size[N],s[N];bool rev[N];inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline bool isroot(int x){    return tree[fa[x]][0]!=x&&tree[fa[x]][1]!=x;}inline void pushup(int x){    size[x]=size[tree[x][0]]+size[tree[x][1]]+1;}inline void pushdown(int x){    if (rev[x])    {        rev[x]^=1; rev[tree[x][0]]^=1; rev[tree[x][1]]^=1;        swap(tree[x][0],tree[x][1]);    }}void rotate(int x){    int y=fa[x],z=fa[y],l=tree[y][1]==x,r=l^1;    if (!isroot(y)) tree[z][tree[z][1]==y]=x;    fa[x]=z; fa[y]=x; fa[tree[x][r]]=y;    tree[y][l]=tree[x][r]; tree[x][r]=y;    pushup(y); pushup(x);}void splay(int x){    int top=0; s[++top]=x;    for (int i=x;!isroot(i);i=fa[i])    {        s[++top]=fa[i];    }    for (int i=top;i;i--) pushdown(s[i]);    while (!isroot(x))    {        int y=fa[x],z=fa[y];        if (!isroot(y))        {            if (tree[y][0]==x^tree[z][0]==y) rotate(x); else rotate(y);        }        rotate(x);    }}void access(int x){    int t=0;    while (x)    {        splay(x);        tree[x][1]=t;        t=x; x=fa[x];    }}void rever(int x){    access(x); splay(x); rev[x]^=1;}void link(int x,int y){    rever(x); fa[x]=y; splay(x);}void cut(int x,int y){    rever(x); access(y); splay(y); tree[y][0]=fa[x]=0;}int main(){    n=read();    for (int i=1;i<=n;i++)    {        int x=read();        fa[i]=x+i; size[i]=1;        if (fa[i]>n+1) fa[i]=n+1;        next[i]=fa[i];    }    size[n+1]=1;    m=read();    for (int i=1;i<=m;i++)    {        int f=read();        if (f==1)        {            rever(n+1);            int x=read(); x++;            access(x); splay(x); printf("%d\n",size[tree[x][0]]);        }        else        {            int x=read(),y=read(); x++;            int t=min(n+1,x+y);            cut(x,next[x]); link(x,t); next[x]=t;        }    }    return 0;}

分块：

#include<iostream>#include<cstdio>#include<cmath>#define N 200005using namespace std;int n,m,cnt,block;int p[N],s[N],k[N],belong[N];int l[1005],r[1005];inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline int work(int x){    int tmp=0;    while (1)    {        tmp+=s[x];        if (!p[x]) break;        x=p[x];    }    return tmp;}int main(){    n=read(); block=(int)(sqrt(n));    for (int i=1;i<=n;i++) k[i]=read();    if (n%block) cnt=n/block+1; else cnt=n/block;    for (int i=1;i<=cnt;i++)        l[i]=(i-1)*block+1,r[i]=i*block;    r[cnt]=n;    for (int i=1;i<=n;i++) belong[i]=(i-1)/block+1;    for (int i=n;i;i--)        if (i+k[i]>n) s[i]=1;        else if (belong[i]==belong[i+k[i]])            s[i]=s[i+k[i]]+1,p[i]=p[i+k[i]];        else s[i]=1,p[i]=i+k[i];    m=read();    while (m--)    {        int f=read(),x=read(),y;        x++;        if (f==1) printf("%d\n",work(x));        else        {            y=read(); k[x]=y;            for (int i=x;i>=l[belong[x]];i--)                if (belong[i]==belong[i+k[i]])                    s[i]=s[i+k[i]]+1,p[i]=p[i+k[i]];                else s[i]=1,p[i]=i+k[i];        }    }    return 0;}