POJ 1442 Black Box(Treap)

来源：互联网发布：中国煤炭资源知乎编辑：程序博客网时间：2024/06/04 18:32

题意：有一些操作，第一种是向集合中添加一个数字，另一种是查找集合中第k大的数字是多少。

思路：用Treap直接搞就行了，可以用来练练手……

代码：

#include <iostream>#include<cstdio>#include<cstring>#include<string>#include<algorithm>#include<map>#include<queue>#include<stack>#include<cmath>#include<vector>#define inf 0x3f3f3f3f#define Inf 0x3FFFFFFFFFFFFFFFLL#define eps 1e-9#define pi acos(-1.0)using namespace std;typedef long long ll;const int maxn=30000+1000;int ch[maxn][2],val[maxn],counts[maxn],r[maxn],size[maxn],tot,root;void Newnode(int &rt,int v){    rt=++tot;    val[rt]=v;    ch[rt][0]=ch[rt][1]=0;    counts[rt]=size[rt]=1;    r[rt]=rand();}inline void PushUp(int rt){    size[rt]=size[ch[rt][0]]+size[ch[rt][1]]+counts[rt];}void Rotate(int &x,int kind){    int y=ch[x][kind^1];    ch[x][kind^1]=ch[y][kind];    ch[y][kind]=x;    PushUp(x);PushUp(y);    x=y;}void Insert(int &rt,int v){    if(rt==0)    {        Newnode(rt,v);        return ;    }    if(v==val[rt]) counts[rt]++;    else    {        int kind=(v>val[rt]);        Insert(ch[rt][kind],v);        if(r[ch[rt][kind]]<r[rt])            Rotate(rt,kind^1);    }    PushUp(rt);}int select(int rt,int k){    if(size[ch[rt][0]]>=k) return select(ch[rt][0],k);    if(size[ch[rt][0]]+counts[rt]>=k) return val[rt];    return select(ch[rt][1],k-size[ch[rt][0]]-counts[rt]);}void Init(){    ch[0][0]=ch[0][1]=0;    size[0]=counts[0]=val[0]=0;    tot=root=0;    Newnode(root,2000000001);}int num[maxn],query[maxn];int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int m,n;    while(~scanf("%d%d",&m,&n))    {        for(int i=0;i<m;++i)            scanf("%d",&num[i]);        for(int i=0;i<n;++i)            scanf("%d",&query[i]);        Init();        int s=0,cnt=0;        for(int i=0;i<m;++i)        {            Insert(root,num[i]);            if(s>=n) break;            while(size[root]-1==query[s])            {                printf("%d\n",select(root,++cnt));                s++;            }        }    }    return 0;}

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