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A15433. Playing with GCD

编程题 普及/提高-

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 $y$ .

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 $10^5$ .

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.
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