| Codeforces Round 1080 (Div. 3) |
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You are given a permutation $$$a$$$ of length $$$n$$$$$$^{\text{∗}}$$$.
You can perform the following operation any number of times (possibly zero):
For example, when $$$a=[1,4,2,3,5]$$$, you can swap $$$a_2$$$ and $$$a_4$$$ to make it $$$[1,3,2,4,5]$$$, but you cannot swap $$$a_2$$$ and $$$a_3$$$.
Please determine if the sequence $$$a$$$ can be sorted in increasing order.
$$$^{\text{∗}}$$$A permutation of length $$$n$$$ is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array), and $$$[1,3,4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).
Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 10^4$$$). The description of the test cases follows.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 2 \cdot 10^5$$$).
The second line of each test case contains $$$n$$$ distinct integers $$$a_1,a_2,\ldots,a_n$$$ ($$$1 \le a_i \le n$$$).
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.
If $$$a$$$ can be sorted in increasing order, output "YES" on a separate line. Otherwise, output "NO" on a separate line.
You can output the answer in any case. For example, the strings "yEs", "yes", and "Yes" will also be recognized as positive responses.
251 4 3 2 551 4 2 3 5
YESNO
In the first test case, $$$a$$$ is $$$[1,4,3,2,5]$$$. You can sort $$$a$$$ in increasing order by swapping $$$a_2$$$ and $$$a_4$$$. Therefore, the answer is "YES".
In the second test case, $$$a$$$ is $$$[1,4,2,3,5]$$$. It is impossible to sort $$$a$$$ in increasing order. Therefore, the answer is "NO".
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