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A14168 | Nastia and a Good Array

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题目描述

Nastia has received an array of $n$ positive integers as a gift.

She calls such an array $a$ good that for all $i$ ( $2 \le i \le n$ ) takes place $gcd(a_{i - 1}, a_{i}) = 1$ , where $gcd(u, v)$ denotes the [greatest common divisor (GCD)](https://en.wikipedia.org/wiki/Greatest_common_divisor) of integers $u$ and $v$ .

You can perform the operation: select two different indices $i, j$ ( $1 \le i, j \le n$ , $i \neq j$ ) and two integers $x, y$ ( $1 \le x, y \le 2 \cdot 10^9$ ) so that $\min{(a_i, a_j)} = \min{(x, y)}$ . Then change $a_i$ to $x$ and $a_j$ to $y$ .

The girl asks you to make the array good using at most $n$ operations.

It can be proven that this is always possible.

输入格式

The first line contains a single integer $t$ ( $1 \le t \le 10\,000$ ) — the number of test cases.

The first line of each test case contains a single integer $n$ ( $1 \le n \le 10^5$ ) — the length of the array.

The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_{n}$ ( $1 \le a_i \le 10^9$ ) — the array which Nastia has received as a gift.

It's guaranteed that the sum of $n$ in one test doesn't exceed $2 \cdot 10^5$ .

输出格式

For each of $t$ test cases print a single integer $k$ ( $0 \le k \le n$ ) — the number of operations. You don't need to minimize this number.

In each of the next $k$ lines print $4$ integers $i$ , $j$ , $x$ , $y$ ( $1 \le i \neq j \le n$ , $1 \le x, y \le 2 \cdot 10^9$ ) so that $\min{(a_i, a_j)} = \min{(x, y)}$ — in this manner you replace $a_i$ with $x$ and $a_j$ with $y$ .

If there are multiple answers, print any.

输入输出样例

输入 #1
2
5
9 6 3 11 15
3
7 5 13
输出 #1
2
1 5 11 9
2 5 7 6
0
C++ 编辑器
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