C Just h-index

鏈接：https://ac.nowcoder.com/acm/contest/1107/C
來源：牛客網
 

時間限制：C/C++ 1秒，其他語言2秒
空間限制：C/C++ 131072K，其他語言262144K
Special Judge, 64bit IO Format: %lld

題目描述

The h-index of an author is the largest h where he has at least h papers with citations not less than h.
Bobo has published n papers with citations a1,a2,…,ana_1, a_2, \dots, a_na1​,a2​,…,an​ respectively.
One day, he raises q questions. The i-th question is described by two integers lil_ili​ and rir_iri​, asking the h-index of Bobo if has *only* published papers with citations ali,ali+1,…,aria_{l_i}, a_{l_i + 1}, \dots, a_{r_i}ali​​,ali​+1​,…,ari​​.

輸入描述:

The input consists of several test cases and is terminated by end-of-file.
The first line of each test case contains two integers n and q.
The second line contains n integers a1,a2,…,ana_1, a_2, \dots, a_na1​,a2​,…,an​.
The i-th of last q lines contains two integers lil_ili​ and rir_iri​.

輸出描述:

For each question, print an integer which denotes the answer.

示例1

輸入

複製

5 3
1 5 3 2 1
1 3
2 4
1 5
5 1
1 2 3 4 5
1 5

輸出

複製

2
2
2
3

備註:

* 1≤n,q≤1051 \leq n, q \leq 10^51≤n,q≤105
* 1≤ai≤n1 \leq a_i \leq n1≤ai​≤n
* 1≤li≤ri≤n1 \leq l_i \leq r_i \leq n1≤li​≤ri​≤n
* The sum of n does not exceed 250,000.
* The sum of q does not exceed 250,000.

 

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 150010;
const int M = MAXN * 30;
int tot, a[MAXN];
int T[M], lson[M], rson[M], c[M];
int build(int l, int r) {
	int root = tot++;
	c[root] = 0;
	if (l != r) {
		int mid = (l + r) >> 1;
		lson[root] = build(l, mid);
		rson[root] = build(mid + 1, r);
	}
	return root;
}
int update(int root, int pos, int val, int m) {
	int newroot = tot++, tmp = newroot;
	c[newroot] = c[root] + val;
	int l = 1, r = m;
	while (l < r) {
		int mid = (l + r) >> 1;
		if (pos <= mid) {
			lson[newroot] = tot++; rson[newroot] = rson[root];
			newroot = lson[newroot]; root = lson[root];
			r = mid;
		}
		else {
			rson[newroot] = tot++; lson[newroot] = lson[root];
			newroot = rson[newroot]; root = rson[root];
			l = mid + 1;
		}
		c[newroot] = c[root] + val;
	}
	return tmp;
}
int query(int left_root, int right_root, int l, int r, int w) {
	//cout << c[left_root] << " " << c[right_root] << " " << l << " " << r << " " << w << "\n";
	if (l == r) {
		return l;
	}
	int mid = (l + r) >> 1;
	if (c[rson[right_root]] - c[rson[left_root]] + w >= mid + 1) {
		return query(rson[left_root], rson[right_root], mid + 1, r, w);
	}
	else {
		return query(lson[left_root], lson[right_root], l, mid, w + c[rson[right_root]] - c[rson[left_root]]);
	}
}
const int K = 100005;
int main() {
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	int n, m;
	while (cin >> n >> m) {
		tot = 0;
		T[0] = build(1, K);
		for (int i = 1; i <= n; i++) {
			cin >> a[i];
			T[i] = update(T[i - 1], a[i], 1, K);
		}
		while (m--) {
			int a, b;
			cin >> a >> b;
			cout << query(T[a - 1], T[b], 1, K, 0) << "\n";
		}
	}
	return 0;
}