Technocup 2022 - Elimination Round 3
D
Yet Another Sorting Problem
Codeforces
1900
原题
← CE →
翻译中…

Petya has an array of integers $a_1, a_2, \ldots, a_n$. He only likes sorted arrays. Unfortunately, the given array could be arbitrary, so Petya wants to sort it.

翻译中…

Petya likes to challenge himself, so he wants to sort array using only $3$-cycles. More formally, in one operation he can pick $3$ pairwise distinct indices $i$, $j$, and $k$ ($1 \leq i, j, k \leq n$) and apply $i \to j \to k \to i$ cycle to the array $a$. It simultaneously places $a_i$ on position $j$, $a_j$ on position $k$, and $a_k$ on position $i$, without changing any other element.

翻译中…

For example, if $a$ is $[10, 50, 20, 30, 40, 60]$ and he chooses $i = 2$, $j = 1$, $k = 5$, then the array becomes $[\underline{50}, \underline{40}, 20, 30, \underline{10}, 60]$.

翻译中…

Petya can apply arbitrary number of $3$-cycles (possibly, zero). You are to determine if Petya can sort his array $a$, i. e. make it non-decreasing.

翻译中…

Input

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Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \leq t \leq 5 \cdot 10^5$). Description of the test cases follows.

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

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The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \leq a_i \leq n$).

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It is guaranteed that the sum of $n$ over all test cases does not exceed $5 \cdot 10^5$.

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Output

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For each test case, print "YES" (without quotes) if Petya can sort the array $a$ using $3$-cycles, and "NO" (without quotes) otherwise. You can print each letter in any case (upper or lower).

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Note

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In the $6$-th test case Petya can use the $3$-cycle $1 \to 3 \to 2 \to 1$ to sort the array.

翻译中…

In the $7$-th test case Petya can apply $1 \to 3 \to 2 \to 1$ and make $a = [1, 4, 2, 3]$. Then he can apply $2 \to 4 \to 3 \to 2$ and finally sort the array.

翻译中…

样例

Input #1
7
1
1
2
2 2
2
2 1
3
1 2 3
3
2 1 3
3
3 1 2
4
2 1 4 3
Output #1
YES
YES
NO
YES
NO
YES
YES
InputCopy OutputCopy
题目信息
题号
1585D
时间限制
2 s
内存限制
256 MB
标签
数据结构
数学

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。