A14426 | Manhattan Subarrays
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内存限制256MB
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题目描述
Suppose you have two points $p = (x_p, y_p)$ and $q = (x_q, y_q)$ . Let's denote the Manhattan distance between them as $d(p, q) = |x_p - x_q| + |y_p - y_q|$ .
Let's say that three points $p$ , $q$ , $r$ form a bad triple if $d(p, r) = d(p, q) + d(q, r)$ .
Let's say that an array $b_1, b_2, \dots, b_m$ is good if it is impossible to choose three distinct indices $i$ , $j$ , $k$ such that the points $(b_i, i)$ , $(b_j, j)$ and $(b_k, k)$ form a bad triple.
You are given an array $a_1, a_2, \dots, a_n$ . Calculate the number of good subarrays of $a$ . A subarray of the array $a$ is the array $a_l, a_{l + 1}, \dots, a_r$ for some $1 \le l \le r \le n$ .
Note that, according to the definition, subarrays of length $1$ and $2$ are good.
Let's say that three points $p$ , $q$ , $r$ form a bad triple if $d(p, r) = d(p, q) + d(q, r)$ .
Let's say that an array $b_1, b_2, \dots, b_m$ is good if it is impossible to choose three distinct indices $i$ , $j$ , $k$ such that the points $(b_i, i)$ , $(b_j, j)$ and $(b_k, k)$ form a bad triple.
You are given an array $a_1, a_2, \dots, a_n$ . Calculate the number of good subarrays of $a$ . A subarray of the array $a$ is the array $a_l, a_{l + 1}, \dots, a_r$ for some $1 \le l \le r \le n$ .
Note that, according to the definition, subarrays of length $1$ and $2$ are good.
输入格式
The first line contains one integer $t$ ( $1 \le t \le 5000$ ) — the number of test cases.
The first line of each test case contains one integer $n$ ( $1 \le n \le 2 \cdot 10^5$ ) — the length of array $a$ .
The second line of each test case contains $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \le a_i \le 10^9$ ).
It's guaranteed that the sum of $n$ doesn't exceed $2 \cdot 10^5$ .
The first line of each test case contains one integer $n$ ( $1 \le n \le 2 \cdot 10^5$ ) — the length of array $a$ .
The second line of each test case contains $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \le a_i \le 10^9$ ).
It's guaranteed that the sum of $n$ doesn't exceed $2 \cdot 10^5$ .
输出格式
For each test case, print the number of good subarrays of array $a$ .
输入输出样例
输入 #1
3 4 2 4 1 3 5 6 9 1 9 6 2 13 37
输出 #1
10 12 3
In the first test case, it can be proven that any subarray of $a$ is good. For example, subarray $[a_2, a_3, a_4]$ is good since it contains only three elements and:
- $d((a_2, 2), (a_4, 4)) = |4 - 3| + |2 - 4| = 3$ $<$ $d((a_2, 2), (a_3, 3)) + d((a_3, 3), (a_4, 4)) = 3 + 1 + 2 + 1 = 7$ ;
- $d((a_2, 2), (a_3, 3))$ $<$ $d((a_2, 2), (a_4, 4)) + d((a_4, 4), (a_3, 3))$ ;
- $d((a_3, 3), (a_4, 4))$ $<$ $d((a_3, 3), (a_2, 2)) + d((a_2, 2), (a_4, 4))$ ;
In the second test case, for example, subarray $[a_1, a_2, a_3, a_4]$ is not good, since it contains a bad triple $(a_1, 1)$ , $(a_2, 2)$ , $(a_4, 4)$ :
- $d((a_1, 1), (a_4, 4)) = |6 - 9| + |1 - 4| = 6$ ;
- $d((a_1, 1), (a_2, 2)) = |6 - 9| + |1 - 2| = 4$ ;
- $d((a_2, 2), (a_4, 4)) = |9 - 9| + |2 - 4| = 2$ ;
So, $d((a_1, 1), (a_4, 4)) = d((a_1, 1), (a_2, 2)) + d((a_2, 2), (a_4, 4))$ .
- $d((a_2, 2), (a_4, 4)) = |4 - 3| + |2 - 4| = 3$ $<$ $d((a_2, 2), (a_3, 3)) + d((a_3, 3), (a_4, 4)) = 3 + 1 + 2 + 1 = 7$ ;
- $d((a_2, 2), (a_3, 3))$ $<$ $d((a_2, 2), (a_4, 4)) + d((a_4, 4), (a_3, 3))$ ;
- $d((a_3, 3), (a_4, 4))$ $<$ $d((a_3, 3), (a_2, 2)) + d((a_2, 2), (a_4, 4))$ ;
In the second test case, for example, subarray $[a_1, a_2, a_3, a_4]$ is not good, since it contains a bad triple $(a_1, 1)$ , $(a_2, 2)$ , $(a_4, 4)$ :
- $d((a_1, 1), (a_4, 4)) = |6 - 9| + |1 - 4| = 6$ ;
- $d((a_1, 1), (a_2, 2)) = |6 - 9| + |1 - 2| = 4$ ;
- $d((a_2, 2), (a_4, 4)) = |9 - 9| + |2 - 4| = 2$ ;
So, $d((a_1, 1), (a_4, 4)) = d((a_1, 1), (a_2, 2)) + d((a_2, 2), (a_4, 4))$ .
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评测结果：Accepted