309790: CF1736C1. Good Subarrays (Easy Version)
Memory Limit:256 MB
Time Limit:1 S
Judge Style:Text Compare
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Description
Good Subarrays (Easy Version)
题意翻译
定义一个序列是好的,当且仅当序列在 $\left[l,r\right]$ 中,对于任意的 $i$,都有 $a_i\ge i-l+1$。求在给定的含有 $n$ 个数的数列 $a$ 中,有多少个子序列是好的。题目描述
This is the easy version of this problem. In this version, we do not have queries. Note that we have multiple test cases in this version. You can make hacks only if both versions of the problem are solved. 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 $ ). You are given an array $ a $ consisting of $ n $ positive integers. 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.输入输出格式
输入格式
Each test contains multiple test cases. The first line contains the number of test cases $ t $ ( $ 1 \leq t \leq 2 \cdot 10^5 $ ). Description of the test cases follows. The first line of each test case contains an integer $ n $ ( $ 1 \leq n \leq 2 \cdot 10^5 $ ), the length of the array $ a $ . The second line of each test case contains $ n $ space-separated integers $ a_1,a_2,\ldots,a_n $ ( $ 1 \leq a_i \leq n $ ), representing the array $ a $ . It is guaranteed that the sum of $ n $ over all test cases does not exceed $ 2 \cdot 10^5 $ .
输出格式
For each test case, print the number of suitable pairs of indices.
输入输出样例
输入样例 #1
3
3
1 2 3
3
1 1 1
4
2 1 4 3
输出样例 #1
6
3
7