Codeforces Round 772 (Div. 2)
C
Differential Sorting
Codeforces
1200
原题
← BD →
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You are given an array $a$ of $n$ elements.

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Your can perform the following operation no more than $n$ times: Select three indices $x,y,z$ $(1 \leq x \lt y \lt z \leq n)$ and replace $a_x$ with $a_y - a_z$. After the operation, $|a_x|$ need to be less than $10^{18}$.

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Your goal is to make the resulting array non-decreasing. If there are multiple solutions, you can output any. If it is impossible to achieve, you should report it as well.

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Input

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Each test contains multiple test cases. The first line will contain a single integer $t$ $(1 \leq t \leq 10000)$ — the number of test cases. Then $t$ test cases follow.

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The first line of each test case contains a single integer $n$ $(3 \leq n \leq 2 \cdot 10^5)$ — the size of the array $a$.

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The second line of each test case contains $n$ integers $a_1, a_2, \ldots ,a_n$ $(-10^9 \leq a_i \leq 10^9)$, the elements of $a$.

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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, print $-1$ in a single line if there is no solution. Otherwise in the first line you should print a single integer $m$ $(0 \leq m \leq n)$ — number of operations you performed.

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Then the $i$-th of the following $m$ lines should contain three integers $x,y,z$ $(1 \leq x \lt y \lt z \leq n)$— description of the $i$-th operation.

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If there are multiple solutions, you can output any. Note that you don't have to minimize the number of operations in this task.

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Note

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In the first example, the array becomes

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$[-6,-4,2,-1,2]$ after the first operation,

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$[-6,-4,-3,-1,2]$ after the second operation.

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In the second example, it is impossible to make the array sorted after any sequence of operations.

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In the third example, the array is already sorted, so we don't need to perform any operations.

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样例

Input #1
3
5
5 -4 2 -1 2
3
4 3 2
3
-3 -2 -1
Output #1
2
1 2 3
3 4 5
-1
0
InputCopy OutputCopy
题目信息
题号
1635C
时间限制
2 s
内存限制
256 MB
标签
构造
贪心

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