Codeforces Round 673 (Div. 2)
D
Make Them Equal
Codeforces
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原题
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You are given an array $a$ consisting of $n$ positive integers, numbered from $1$ to $n$. You can perform the following operation no more than $3n$ times:

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  1. choose three integers $i$, $j$ and $x$ ($1 \le i, j \le n$; $0 \le x \le 10^9$);
  2. assign $a_i := a_i - x \cdot i$, $a_j := a_j + x \cdot i$.
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After each operation, all elements of the array should be non-negative.

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Can you find a sequence of no more than $3n$ operations after which all elements of the array are equal?

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Input

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The first line contains one integer $t$ ($1 \le t \le 10^4$) — the number of test cases. Then $t$ test cases follow.

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The first line of each test case contains one integer $n$ ($1 \le n \le 10^4$) — the number of elements in the array. The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 10^5$) — the elements of the array.

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It is guaranteed that the sum of $n$ over all test cases does not exceed $10^4$.

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Output

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For each test case print the answer to it as follows:

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  • if there is no suitable sequence of operations, print $-1$;
  • otherwise, print one integer $k$ ($0 \le k \le 3n$) — the number of operations in the sequence. Then print $k$ lines, the $m$-th of which should contain three integers $i$, $j$ and $x$ ($1 \le i, j \le n$; $0 \le x \le 10^9$) for the $m$-th operation.
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If there are multiple suitable sequences of operations, print any of them. Note that you don't have to minimize $k$.

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样例

Input #1
3
4
2 16 4 18
6
1 2 3 4 5 6
5
11 19 1 1 3
Output #1
2
4 1 2
2 3 3
-1
4
1 2 4
2 4 5
2 3 3
4 5 1
InputCopy OutputCopy
题目信息
题号
1417D
时间限制
1 s
内存限制
256 MB

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。