bzoj2002

非常好的一篇博客(LCT)

时间效率相差不大

1.分块

#include<cstdio>
#include<cmath>
#include<cctype>
using namespace std;
const int maxn=200004;
int n,cnt,num,whic[maxn],a[maxn],l[510],r[510],muc[maxn],nex[maxn];
 
 
inline int read(){
    char ch=getchar();int k=0;
    while(!isdigit(ch)) ch=getchar();
    while(isdigit(ch)){k=(k<<1)+(k<<3)+ch-'0';ch=getchar();}
    return k;
}
 
int query(int x){
   int t=0;for(;x;t+=muc[x],x=nex[x]);return t;
} 
 
int main(){
    n=read();
    for(int i=1;i<=n;i++) a[i]=read();
    num=sqrt(n);
    if(n%num)cnt=n/num+1;else cnt=n/num;
    for(int i=1,j=num;i<=cnt;i++,j+=num) {l[i]=r[i-1]+1;r[i]=j;}r[cnt]=n;
    for(int i=1;i<=n;i++) whic[i]=(i-1)/num+1;
    for(int i=n;i>=1;i--){
        if(i+a[i]>n) muc[i]=1;
        else if(whic[i]==whic[i+a[i]]) {muc[i]=muc[i+a[i]]+1;nex[i]=nex[i+a[i]];}
        else muc[i]=1,nex[i]=i+a[i];
    }
    int m=read();
    while(m--){
        int flag=read(),x=read()+1;
        if(flag==1) printf("%d\n",query(x));
        else{
            int y=read();a[x]=y;
            for(int i=x;i>=l[whic[x]];i--){
                if(whic[i]==whic[i+a[i]]) muc[i]=muc[i+a[i]]+1,nex[i]=nex[i+a[i]];
                else muc[i]=1,nex[i]=i+a[i];
            }
        }
    }
    return 0;
} 

2.LCT

思路概要：把该点连向跳到的点，并保证跳到的点深度比他小，则最后左儿子的siz+1即答案

#include<cstdio>
#include<cctype>
#include<algorithm>
#define ls tr[x][0]
#define rs tr[x][1]
#define maxn 300100
using namespace std;
int n,f[maxn],siz[maxn],tr[maxn][2],rev[maxn],tmp[maxn];
inline void pushup(int x){siz[x]=siz[tr[x][0]]+siz[tr[x][1]]+1;}
inline void pushr(int x){if(rev[x])swap(ls,rs);rev[x]^=1;}
inline void pushdown(int x){if(rev[x]){if(ls)pushr(ls);if(rs)pushr(rs);rev[x]=0;}}
inline bool isroot(int x){return (tr[f[x]][0]==x||tr[f[x]][1]==x);}
inline void read(int &x){
    char ch=getchar();x=0;int f=1;
    while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
    while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    x*=f;
}
inline void rotate(int x){
    int fa=f[x],gfa=f[fa],whicx=tr[fa][1]==x,flag=isroot(fa);
    tr[fa][whicx]=tr[x][whicx^1];f[tr[fa][whicx]]=fa;
    tr[x][whicx^1]=fa;f[fa]=x;
    f[x]=gfa;if(flag)tr[gfa][tr[gfa][1]==fa]=x;
    pushup(fa);
}
inline void splay(int x){
    int y=x,siz=0,z;
    tmp[++siz]=y;
    while(isroot(y))tmp[++siz]=y=f[y];
    while(siz)pushdown(tmp[siz--]);
    while(isroot(x)){
        y=f[x];z=f[y];
        if(isroot(y))rotate((tr[y][1]==x)==(tr[z][1]==y)?y:x);
        if(isroot(x))rotate(x);
    }
    pushup(x);
}
inline void access(int x){for(int y=0;x;x=f[y=x])splay(x),rs=y,pushup(x);}
inline void makeroot(int x){access(x);splay(x);pushr(x);}
inline int findroot(int x){
    access(x);splay(x);pushdown(x);
    while(ls)x=ls,pushdown(x);
    return x;
}
inline void cut(int x){access(x);splay(x);tr[x][0]=f[tr[x][0]]=0;}
inline void link(int x,int y){makeroot(x);f[x]=y;}
int main(){
    read(n);int k;
    for(int i=1;i<=n;i++)read(k),f[i]=i+k>n?0:i+k,siz[i]=1;
    int m,typ,x,y;read(m);
    while(m--){
        read(typ);read(x);x++;
        if(typ==1){access(x);splay(x);printf("%d\n",siz[tr[x][0]]+1);}
        else {cut(x);read(y);link(x,x+y>n?0:x+y);}
    }
}