（区间第k大）黑匣子_NOI导刊2010提高（06）

https://www.luogu.org/problemnew/show/P1801
可以用multiset水过，发现有超多数据结构可以处理这道题。==
线段树：https://blog.csdn.net/weishengmingerfendou/article/details/47144419
fhq-treap：https://blog.csdn.net/CABI_ZGX/article/details/79963427

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 10;
#define inf 2000000010
#define eps 0.000003
#define lson rt<<1, l, m
#define rson rt<<1|1, m+1, r

multiset<int> mp;
multiset<int> ::iterator it;
int a[maxn], q[maxn];
int main()
{
    int n, m, x, k = 1;
    scanf("%d%d", &n, &m);
    register int i;
    for(i = 1; i <= n; i++) scanf("%d", &a[i]);
    for(i = 1; i <= m; i++) scanf("%d", &q[i]);
    mp.insert(a[1]);
    it = mp.begin();
    if(q[1] == 1) printf("%d\n", a[1]), k++;
    for(i = 2; i <= n; i++) {
        mp.insert(a[i]);
        if(a[i] < *it) it--;
        while(q[k] == i) {
            if(k != 1) it++;
            printf("%d\n", *it);
            k++;
        }
    }
}

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