A15433. Playing with GCD
编程题
普及/提高-
知识点
题目描述
You are given an integer array $a$ of length $n$ .
Does there exist an array $b$ consisting of $n+1$ positive integers such that $a_i=\gcd (b_i,b_{i+1})$ for all $i$ ( $1 \leq i \leq n$ )?
Note that $\gcd(x, y)$ denotes the [greatest common divisor (GCD)](https://en.wikipedia.org/wiki/Greatest_common_divisor) of integers $x$ and $y$ .
Does there exist an array $b$ consisting of $n+1$ positive integers such that $a_i=\gcd (b_i,b_{i+1})$ for all $i$ ( $1 \leq i \leq n$ )?
Note that $\gcd(x, y)$ denotes the [greatest common divisor (GCD)](https://en.wikipedia.org/wiki/Greatest_common_divisor) of integers $x$ and $y$ .
输入格式
Each test contains multiple test cases. The first line contains the number of test cases $t$ ( $1 \leq t \leq 10^5$ ). Description of the test cases follows.
The first line of each test case contains an integer $n$ ( $1 \leq n \leq 10^5$ ) — the length of the array $a$ .
The second line of each test case contains $n$ space-separated integers $a_1,a_2,\ldots,a_n$ representing the array $a$ ( $1 \leq a_i \leq 10^4$ ).
It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$ .
The first line of each test case contains an integer $n$ ( $1 \leq n \leq 10^5$ ) — the length of the array $a$ .
The second line of each test case contains $n$ space-separated integers $a_1,a_2,\ldots,a_n$ representing the array $a$ ( $1 \leq a_i \leq 10^4$ ).
It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$ .
输出格式
For each test case, output "YES" if such $b$ exists, otherwise output "NO". You can print each letter in any case (upper or lower).
输入输出样例
输入 #1
4 1 343 2 4 2 3 4 2 4 4 1 1 1 1
输出 #1
YES YES NO YES
说明/提示
In the first test case, we can take $b=[343,343]$ .
In the second test case, one possibility for $b$ is $b=[12,8,6]$ .
In the third test case, it can be proved that there does not exist any array $b$ that fulfills all the conditions.
In the second test case, one possibility for $b$ is $b=[12,8,6]$ .
In the third test case, it can be proved that there does not exist any array $b$ that fulfills all the conditions.