Luogu P1533 可怜的狗狗

#include <bits/stdc++.h>

#define ll long long
#define inf 0x7fffffff
#define il inline

namespace io {

    #define in(a) a=read()
    #define out(a) write(a)
    #define outn(a) out(a),putchar(‘\n‘)

    #define I_int int
    inline I_int read() {
        I_int x = 0 , f = 1 ; char c = getchar() ;
        while( c < ‘0‘ || c > ‘9‘ ) { if( c == ‘-‘ ) f = -1 ; c = getchar() ; }
        while( c >= ‘0‘ && c <= ‘9‘ ) { x = x * 10 + c - ‘0‘ ; c = getchar() ; }
        return x * f ;
    }
    char F[ 200 ] ;
    inline void write( I_int x ) {
        if( x == 0 ) { putchar( ‘0‘ ) ; return ; }
        I_int tmp = x > 0 ? x : -x ;
        if( x < 0 ) putchar( ‘-‘ ) ;
        int cnt = 0 ;
        while( tmp > 0 ) {
            F[ cnt ++ ] = tmp % 10 + ‘0‘ ;
            tmp /= 10 ;
        }
        while( cnt > 0 ) putchar( F[ -- cnt ] ) ;
    }
    #undef I_int

}
using namespace io ;

using namespace std ;

#define N 300010
#define int long long 

int n , tot = 0, root = 1; 

//fhq-treap
struct fhq_treap {
    int siz , val , lc , rc , rnk ;
} t[N] ;
void pushup(int rt) {t[rt].siz = t[t[rt].lc].siz + t[t[rt].rc].siz + 1 ;}
void split(int &a , int &b , int val , int rt) {
    if(!rt) { a = b = 0 ; return ; }
    if(t[rt].val <= val) a = rt , split(t[a].rc , b , val , t[rt].rc) ;
    else b = rt , split(a , t[b].lc , val , t[rt].lc) ;
    pushup(rt) ;
}
void merge(int a , int b , int &rt) {
    if(!a || !b) {rt = a + b ; return ;}
    if(t[a].rnk < t[b].rnk) rt = a , merge(t[a].rc , b , t[rt].rc) ;
    else rt = b , merge(a , t[b].lc , t[rt].lc) ;
    pushup(rt) ;
} 
int new_node(int val) {
    t[++tot] = (fhq_treap) {1 , val , 0 , 0 , rand()} ;
    return tot ;
}
inline void insert(int val) {
    int x = 0 , y = 0 , z = new_node(val) ;
    split(x , y , val , root) ;
    merge(x , z , x) ; merge(x , y , root) ;
}
void Del(int val) {
    int x = 0 , y = 0 , z = 0 ;
    split(x , y , val , root) ; split(x , z , val - 1 , x) ;
    merge(t[z].lc , t[z].rc , z) ; merge(x , z , x) ; merge(x , y , root) ;
}
inline int find_val(int rnk , int rt) {
    while(t[t[rt].lc].siz + 1 != rnk) {
        if(t[t[rt].lc].siz >= rnk) rt = t[rt].lc ;
        else rnk -= t[t[rt].lc].siz + 1 , rt = t[rt].rc ;
    }
    return t[rt].val ;
}
//fhq-treap end

struct query {
    int l , r , val , id;
} q[N] ;
int ans[N] , a[N] , block ;

bool cmp(query a , query b) {
    return a.l == b.l ? a.r < b.r : a.l < b.l ;
}

signed main() {
#ifndef ONLINE_JUDGE
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
#endif
    srand((unsigned)time(0)) ;
    n = read() ; int m = read() ;
    new_node(inf) ; t[1].siz = 0 ;
    for(int i = 1 ; i <= n ; i ++) a[i] = read() ;
    for(int i = 1 ; i <= m ; i ++) q[i] = (query) {read() , read() , read() , i} ;
    block = sqrt(n) ; sort(q + 1 , q + m + 1 , cmp) ;
    q[0].l = 1 ;
    for(int i = 1 ; i <= m ; i ++) {
        for(int cur = q[i-1].r + 1 ; cur <= q[i].r ; cur ++) insert(a[cur]) ;
        for(int cur = q[i-1].l ; cur < q[i].l ; cur ++) Del(a[cur]) ;
        ans[q[i].id] = find_val(q[i].val , root) ;
    }
    for(int i = 1 ; i <= m ; i ++) outn(ans[i]) ;
}