【主席树】51Nod 1175 区间中第K大的数

题面在这里

主席树裸题……

联赛快来了还是练练手速吧

示例程序：

#include<cstdio>#include<algorithm>using namespace std;inline char nc(){    static char buf[100000],*p1=buf,*p2=buf;    return p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++;}inline int red(){    int res=0,f=1;char ch=nc();    while (ch<'0'||'9'<ch) {if (ch=='-') f=-f;ch=nc();}    while ('0'<=ch&&ch<='9') res=(res<<3)+(res<<1)+ch-48,ch=nc();    return res*f;}const int maxn=50005,maxs=900000;int n,m,q,a[maxn],b[maxn];inline int ID(int x){    return lower_bound(b+1,b+1+m,x)-b;}struct node{    node *l,*r;    int s;    node () {}    node (node *_l,node *_r):l(_l),r(_r),s(0) {}    void pushup() {s=l->s+r->s;}}nil,base[maxs];typedef node* P_node;P_node null,len,Rot[maxn];void init(){    nil=node(null,null);null=&nil;    len=base;}inline P_node newnode(node *l,node *r){    *len=node(l,r);return len++;}P_node build(int L,int R){    P_node x=newnode(null,null);    if (L==R) return x;    int mid=L+R>>1;    x->l=build(L,mid);x->r=build(mid+1,R);    return x;}P_node insert(P_node fa,int k,int L,int R){    P_node x=newnode(fa->l,fa->r);    if (L==R) {x->s=fa->s+1;return x;}    int mid=L+R>>1;    if (k<=mid) x->l=insert(fa->l,k,L,mid);else x->r=insert(fa->r,k,mid+1,R);    x->pushup(); return x;}int query(P_node l,P_node r,int k,int L,int R){    if (L==R) return L;    int mid=L+R>>1;    if (k<= r->l->s - l->l->s) return query(l->l,r->l,k,L,mid);else     return query(l->r,r->r,k- (r->l->s - l->l->s),mid+1,R);}int main(){    n=red();    for (int i=1;i<=n;i++) a[i]=b[i]=red();    sort(b+1,b+1+n);    m=unique(b+1,b+1+n)-b-1;    init();Rot[0]=build(1,m);    for (int i=1;i<=n;i++) Rot[i]=insert(Rot[i-1],ID(a[i]),1,m);    q=red();    while (q--){        int l=red()+1,r=red()+1,k=red();k=r-l+1-k+1;        printf("%d\n",b[query(Rot[l-1],Rot[r],k,1,m)]);    }    return 0;}