Luogu1801_黑匣子_KEY

题目传送门

借这道题练一下Treap和Splay的板子。

code：

#include <cstdio>
#include <cstdlib>
using namespace std;

int read()
{
    char c;while(c=getchar(),(c<''||c>'')&&c!='-');
    int x=,y=;c=='-'?y=-:x=c-'';
    while(c=getchar(),c>=''&&c<='')x=x*+c-'';
    return x*y;
}

int N,M,a[],b[];
int root=,tr[][],v[],f[],rd[];
int cnt=;

void rotate(int &x,int o)
{
    int k=tr[x][o];
    tr[x][o]=tr[k][o^];
    tr[k][o^]=x;
    f[k]=f[x];
    f[x]=f[tr[x][]]+f[tr[x][]]+;
    x=k;
}

void insert(int &x,int val)
{
    if(!x){
        x=++cnt;
        v[x]=val;
        f[x]++;
        rd[x]=rand();
        return ;
    }
    f[x]++;
    int to=val>v[x];
    insert(tr[x][to],val);
    if(rd[tr[x][to]]>rd[x])rotate(x,to);
    return ;
}

int Query(int x,int kth)
{
    if(!x)return -;
    if(f[tr[x][]]>=kth)return Query(tr[x][],kth);
    if(f[tr[x][]]+<kth)return Query(tr[x][],kth-f[tr[x][]]-);
    return v[x];
}

int main()
{
    srand();
    N=read(),M=read();
    register int i,j;
        for(i=;i<=N;i++)a[i]=read();
        for(i=;i<=M;i++)b[i]=read();
    j=;
        for(i=;i<=N;i++){
            insert(root,a[i]);
            while(i==b[j])
                printf("%d\n",Query(root,j)),j++;
        }
}

Treap

#include <cstdio>
using namespace std;

int root,cnt;
int tr[][],f[],v[],fa[];

int get(int x){return x==tr[fa[x]][];}
void up(int x){f[x]=f[tr[x][]]+f[tr[x][]]+;}
int rotate(int x)
{
    int ol=fa[x],olol=fa[ol],to=get(x);
    tr[ol][to]=tr[x][to^],fa[tr[x][to^]]=ol;
    tr[x][to^]=ol;fa[ol]=x;
    fa[x]=olol;
    if(olol)
        tr[olol][ol==tr[olol][]]=x;
    up(ol);up(x);
}

void splay(int x)
{
    for(int S;S=fa[x];rotate(x))
        if(fa[S])
            rotate(get(x)==get(S)?S:x);
    root=x;
}

int dist;
void insert(int &x,int val,int pos)
{
    if(!x){
        x=++cnt;
        v[x]=val;
        fa[x]=pos;
        f[x]++;
        dist=cnt;
        return ;
    }
    int to=val>v[x];
    insert(tr[x][to],val,x);
    up(x);
    return ;
}

int Query(int x,int kth)
{
    if(!x)return -;
    if(f[tr[x][]]>=kth)return Query(tr[x][],kth);
    if(f[tr[x][]]+<kth)return Query(tr[x][],kth-f[tr[x][]]-);
    return v[x];
}

int N,M,a[],b[];

int read()
{
    char c;while(c=getchar(),(c<''||c>'')&&c!='-');
    int x=,y=;c=='-'?y=-:x=c-'';
    while(c=getchar(),c>=''&&c<='')x=x*+c-'';
    return x*y;
}

int main()
{
    N=read(),M=read();
    register int i,j;
        for(i=;i<=N;i++)a[i]=read();
        for(i=;i<=M;i++)b[i]=read();
    j=;
        for(i=;i<=N;i++){
            insert(root,a[i],);splay(dist);
            while(i==b[j])printf("%d\n",Query(root,j)),j++;
        }
    return ;
}

Splay