主席树修正

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<queue>
 6 #include<cstring>
 7 #define PAU putchar(' ')
 8 #define ENT putchar('\n')
 9 #define lson x?x->ch[0]:x,y->ch[0],L,M
10 #define rson x?x->ch[1]:x,y->ch[1],M+1,R
11 using namespace std;
12 const int maxn=10000+10,inf=-1u>>1,maxnode=200000+10;
13 struct node{node*ch[2];int siz;node(){siz=0;}}fol[maxnode],*root[maxn],*nodecnt=fol;
14 node*ls(node*x){return x?x->ch[0]:x;}
15 node*rs(node*x){return x?x->ch[1]:x;}
16 int sz(node*x){return x?x->siz:0;}
17 int n,Q,A[maxn],num[maxn];
18 void build(node*x,node*&y,int L,int R,int pos){
19     y=nodecnt++;y->siz=sz(x)+1;if(L==R)return;int M=L+R>>1;
20     if(pos<=M) y->ch[1]=rs(x),build(lson,pos);
21     else y->ch[0]=ls(x),build(rson,pos);
22 }
23 int query(node*x,node*&y,int L,int R,int k){
24     if(L==R)return L;int M=L+R>>1,kth=sz(ls(y))-sz(ls(x));
25     if(k<=kth) return query(lson,k);return query(rson,k-kth);
26 }
27 int find(int v){
28     int L=1,R=n,M;while(L<R){M=L+R>>1;if(num[M]<v)L=M+1;else R=M;}return L;
29 }
30 inline int read(){
31     int x=0,sig=1;char ch=getchar();
32     while(!isdigit(ch)){if(ch=='-') sig=-1;ch=getchar();}
33     while(isdigit(ch)) x=10*x+ch-'0',ch=getchar();
34     return x*=sig;
35 }
36 inline void write(int x){
37     if(x==0){putchar('0');return;}if(x<0) putchar('-'),x=-x;
38     int len=0,buf[15];while(x) buf[len++]=x%10,x/=10;
39     for(int i=len-1;i>=0;i--) putchar(buf[i]+'0');return;
40 }
41 void init(){
42     n=read();Q=read();for(int i=1;i<=n;i++)num[i]=A[i]=read();
43     sort(num+1,num+1+n);for(int i=1;i<=n;i++)build(root[i-1],root[i],1,n,find(A[i]));
44     return;
45 }
46 void work(){
47     int a,b,c;
48     while(Q--){
49         a=read();b=read();c=read();
50         write(num[query(root[a-1],root[b],1,n,c)]);ENT;
51     }
52     return;
53 }
54 void print(){
55     return;
56 }
57 int main(){
58     init();work();print();return 0;
59 }