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<'0'||c>'9')&&c!='-');
    int x=0,y=1;c=='-'?y=-1:x=c-'0';
    while(c=getchar(),c>='0'&&c<='9')x=x*10+c-'0';
    return x*y;
}

int N,M,a[200005],b[200005];
int root=0,tr[200005][2],v[200005],f[200005],rd[200005];
int cnt=0;

void rotate(int &x,int o)
{
    int k=tr[x][o];
    tr[x][o]=tr[k][o^1];
    tr[k][o^1]=x;
    f[k]=f[x];
    f[x]=f[tr[x][0]]+f[tr[x][1]]+1;
    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 -1;
    if(f[tr[x][0]]>=kth)return Query(tr[x][0],kth);
    if(f[tr[x][0]]+1<kth)return Query(tr[x][1],kth-f[tr[x][0]]-1);
    return v[x];
}

int main()
{
    srand(23333);
    N=read(),M=read();
    register int i,j;
        for(i=1;i<=N;i++)a[i]=read();
        for(i=1;i<=M;i++)b[i]=read();
    j=1;
        for(i=1;i<=N;i++){
            insert(root,a[i]);
            while(i==b[j])
                printf("%d\n",Query(root,j)),j++;
        }
}

#include <cstdio>
using namespace std;

int root,cnt;
int tr[200005][2],f[200005],v[200005],fa[200005];

int get(int x){return x==tr[fa[x]][1];}
void up(int x){f[x]=f[tr[x][0]]+f[tr[x][1]]+1;}
int rotate(int x)
{
    int ol=fa[x],olol=fa[ol],to=get(x);
    tr[ol][to]=tr[x][to^1],fa[tr[x][to^1]]=ol;
    tr[x][to^1]=ol;fa[ol]=x;
    fa[x]=olol;
    if(olol)
        tr[olol][ol==tr[olol][1]]=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 -1;
    if(f[tr[x][0]]>=kth)return Query(tr[x][0],kth);
    if(f[tr[x][0]]+1<kth)return Query(tr[x][1],kth-f[tr[x][0]]-1);
    return v[x];
}

int N,M,a[200005],b[200005];

int read()
{
    char c;while(c=getchar(),(c<'0'||c>'9')&&c!='-');
    int x=0,y=1;c=='-'?y=-1:x=c-'0';
    while(c=getchar(),c>='0'&&c<='9')x=x*10+c-'0';
    return x*y;
}

int main()
{
    N=read(),M=read();
    register int i,j;
        for(i=1;i<=N;i++)a[i]=read();
        for(i=1;i<=M;i++)b[i]=read();
    j=1;
        for(i=1;i<=N;i++){
            insert(root,a[i],0);splay(dist);
            while(i==b[j])printf("%d\n",Query(root,j)),j++;
        }
    return 0;
}