Deltix Round, Autumn 2021 (open for everyone, rated, Div. 1 + Div. 2)
C
Complex Market Analysis
Codeforces
1400
原题
← BD →
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image

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While performing complex market analysis William encountered the following problem:

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For a given array $a$ of size $n$ and a natural number $e$, calculate the number of pairs of natural numbers $(i, k)$ which satisfy the following conditions:

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  • $1 \le i, k$
  • $i + e \cdot k \le n$.
  • Product $a_i \cdot a_{i + e} \cdot a_{i + 2 \cdot e} \cdot \ldots \cdot a_{i + k \cdot e} $ is a prime number.
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A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers.

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Input

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Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 10\,000$). Description of the test cases follows.

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The first line of each test case contains two integers $n$ and $e$ $(1 \le e \le n \le 2 \cdot 10^5)$, the number of items in the array and number $e$, respectively.

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The second line contains $n$ integers $a_1, a_2, \dots, a_n$ $(1 \le a_i \le 10^6)$, the contents of the array.

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It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.

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Output

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For each test case output the answer in the following format:

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Output one line containing the number of pairs of numbers $(i, k)$ which satisfy the conditions.

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Note

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In the first example test case two pairs satisfy the conditions:

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  1. $i = 2, k = 1$, for which the product is: $a_{2} \cdot a_{5} = 2$ which is a prime number.
  2. $i = 3, k = 1$, for which the product is: $a_{3} \cdot a_{6} = 19$ which is a prime number.
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In the second example test case there are no pairs that satisfy the conditions.

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In the third example test case four pairs satisfy the conditions:

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  1. $i = 1, k = 1$, for which the product is: $a_{1} \cdot a_{4} = 2$ which is a prime number.
  2. $i = 1, k = 2$, for which the product is: $a_{1} \cdot a_{4} \cdot a_{7} = 2$ which is a prime number.
  3. $i = 3, k = 1$, for which the product is: $a_{3} \cdot a_{6} = 2$ which is a prime number.
  4. $i = 6, k = 1$, for which the product is: $a_{6} \cdot a_{9} = 2$ which is a prime number.
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In the fourth example test case there are no pairs that satisfy the conditions.

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In the fifth example test case five pairs satisfy the conditions:

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  1. $i = 1, k = 1$, for which the product is: $a_{1} \cdot a_{2} = 2$ which is a prime number.
  2. $i = 1, k = 2$, for which the product is: $a_{1} \cdot a_{2} \cdot a_{3} = 2$ which is a prime number.
  3. $i = 1, k = 3$, for which the product is: $a_{1} \cdot a_{2} \cdot a_{3} \cdot a_{4} = 2$ which is a prime number.
  4. $i = 2, k = 1$, for which the product is: $a_{2} \cdot a_{3} = 2$ which is a prime number.
  5. $i = 2, k = 2$, for which the product is: $a_{2} \cdot a_{3} \cdot a_{4} = 2$ which is a prime number.
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In the sixth example test case there are no pairs that satisfy the conditions.

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样例

Input #1
6
7 3
10 2 1 3 1 19 3
3 2
1 13 1
9 3
2 4 2 1 1 1 1 4 2
3 1
1 1 1
4 1
1 2 1 1
2 2
1 2
Output #1
2
0
4
0
5
0
InputCopy OutputCopy
题目信息
题号
1609C
时间限制
2 s
内存限制
256 MB
标签
二分
动态规划
模拟
数论
调度
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。