P17333 "TPOI-2C" Secret Illumination
Background
[Secret Illumination - Yooh](https://www.bilibili.com/video/BV1oG4y1X7bQ)
Description
Given $n, k$, construct an array $a$ of length $n$ that satisfies the following conditions.
- $1 \le a_i \le 10^9$.
- $\displaystyle\sum_{i=1}^{n}\sum_{j=i+1}^{n}[a_i < a_j]\times a_j = k$.
Here, when the condition $case$ holds, the value of $[case]$ is $1$; otherwise it is $0$.
**This problem uses Special Judge. Any answer that satisfies the conditions will be considered correct.**
Input Format
**This problem has multiple test cases.**
The first line contains a positive integer $T$, representing the number of test cases.
The next $T$ lines each contain two integers $n, k$.
Output Format
For each test case, output one line: if there is a solution, output $n$ integers representing your constructed answer; if there is no solution, output `-1`.
Explanation/Hint
**[Sample #1 Explanation]**
For the first test case, we have $3+4+4+4=15$. Another valid answer is `4 2 1 5`, and the value of the expression in the statement is also exactly $5+5+5=15$.
For the second test case, it is clearly impossible to construct a valid answer.
**[Constraints]**
**This problem uses bundled tests.**
|$\text{Subtask}$|Score|Special property|
|:-:|:-:|:-:|
|$0$|$0$|Sample|
|$1$|$20$|$n, k \le 8$|
|$2$|$20$|$k \le 10^9$|
|$3$|$20$|$n \le 500$|
|$4$|$20$|$n \le 5000$|
|$5$|$20$|None|
For $100\%$ of the testdata, it is guaranteed that $1 \le T \le 50$, $1 \le n \le 2 \times 10^5$, and $0 \le k \le 10^{18}$.
Note: Incorrect code may cause Special Judge to exceed the time limit, in which case the result will be shown as UKE. Please be sure to take note.
Translated by ChatGPT 5