Codeforces Round 825 (Div. 2)
C2
Good Subarrays (Hard Version)
Codeforces
2400
原题
← C1D →
翻译中…

This is the hard version of this problem. In this version, we have queries. Note that we do not have multiple test cases in this version. You can make hacks only if both versions of the problem are solved.

翻译中…

An array $b$ of length $m$ is good if for all $i$ the $i$-th element is greater than or equal to $i$. In other words, $b$ is good if and only if $b_i \geq i$ for all $i$ ($1 \leq i \leq m$).

翻译中…

You are given an array $a$ consisting of $n$ positive integers, and you are asked $q$ queries.

翻译中…

In each query, you are given two integers $p$ and $x$ ($1 \leq p,x \leq n$). You have to do $a_p := x$ (assign $x$ to $a_p$). In the updated array, find the number of pairs of indices $(l, r)$, where $1 \le l \le r \le n$, such that the array $[a_l, a_{l+1}, \ldots, a_r]$ is good.

翻译中…

Note that all queries are independent, which means after each query, the initial array $a$ is restored.

翻译中…

Input

翻译中…

The first line contains a single integer $n$ ($1 \le n \le 2 \cdot 10^5$).

翻译中…

The second line contains $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \le a_i \le n$).

翻译中…

The third line contains an integer $q$ ($1 \leq q \leq 2 \cdot 10^5$) — the number of queries.

翻译中…

Each of the next $q$ lines contains two integers $p_j$ and $x_j$ ($1 \leq p_j, x_j \leq n$) – the description of the $j$-th query.

翻译中…

Output

翻译中…

For each query, print the number of suitable pairs of indices after making the change.

翻译中…

Note

翻译中…

Here are notes for first example.

翻译中…

In first query, after update $a=[2,4,1,4]$. Now $(1,1)$, $(2,2)$, $(3,3)$, $(4,4)$, $(1,2)$, and $(3,4)$ are suitable pairs.

翻译中…

In second query, after update $a=[2,4,3,4]$. Now all subarrays of $a$ are good.

翻译中…

In third query, after update $a=[2,1,1,4]$. Now $(1,1)$, $(2,2)$, $(3,3)$, $(4,4)$, and $(3,4)$ are suitable.

翻译中…

样例

Input #1
4
2 4 1 4
3
2 4
3 3
2 1
Output #1
6
10
5
InputCopy OutputCopy
Input #2
5
1 1 3 2 1
3
1 3
2 5
4 5
Output #2
7
9
8
InputCopy OutputCopy
题目信息
题号
1736C2
时间限制
3 s
内存限制
256 MB
标签
二分
数据结构
动态规划
双指针

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。