A14958. Reverse
编程题
普及/提高-
知识点
题目描述
You are given a permutation $p_1, p_2, \ldots, p_n$ of length $n$ . You have to choose two integers $l,r$ ( $1 \le l \le r \le n$ ) and reverse the subsegment $[l,r]$ of the permutation. The permutation will become $p_1,p_2, \dots, p_{l-1},p_r,p_{r-1}, \dots, p_l,p_{r+1},p_{r+2}, \dots ,p_n$ .
Find the lexicographically smallest permutation that can be obtained by performing exactly one reverse operation on the initial permutation.
Note that for two distinct permutations of equal length $a$ and $b$ , $a$ is lexicographically smaller than $b$ if at the first position they differ, $a$ has the smaller element.
A permutation 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).
Find the lexicographically smallest permutation that can be obtained by performing exactly one reverse operation on the initial permutation.
Note that for two distinct permutations of equal length $a$ and $b$ , $a$ is lexicographically smaller than $b$ if at the first position they differ, $a$ has the smaller element.
A permutation 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).
输入格式
Each test contains multiple test cases. The first line contains a single integer $t$ ( $1 \le t \le 500$ ) — the number of test cases. Description of the test cases follows.
The first line of each test case contains a single integer $n$ ( $1 \le n \le 500$ ) — the length of the permutation.
The second line of each test case contains $n$ integers $p_1, p_2, \dots, p_n$ ( $1 \le p_i \le n$ ) — the elements of the permutation.
The first line of each test case contains a single integer $n$ ( $1 \le n \le 500$ ) — the length of the permutation.
The second line of each test case contains $n$ integers $p_1, p_2, \dots, p_n$ ( $1 \le p_i \le n$ ) — the elements of the permutation.
输出格式
For each test case print the lexicographically smallest permutation you can obtain.
输入输出样例
输入 #1
4 1 1 3 2 1 3 4 1 4 2 3 5 1 2 3 4 5
输出 #1
1 1 2 3 1 2 4 3 1 2 3 4 5
说明/提示
In the first test case, the permutation has length $1$ , so the only possible segment is $[1,1]$ . The resulting permutation is $[1]$ .
In the second test case, we can obtain the identity permutation by reversing the segment $[1,2]$ . The resulting permutation is $[1,2,3]$ .
In the third test case, the best possible segment is $[2,3]$ . The resulting permutation is $[1,2,4,3]$ .
In the fourth test case, there is no lexicographically smaller permutation, so we can leave it unchanged by choosing the segment $[1,1]$ . The resulting permutation is $[1,2,3,4,5]$ .
In the second test case, we can obtain the identity permutation by reversing the segment $[1,2]$ . The resulting permutation is $[1,2,3]$ .
In the third test case, the best possible segment is $[2,3]$ . The resulting permutation is $[1,2,4,3]$ .
In the fourth test case, there is no lexicographically smaller permutation, so we can leave it unchanged by choosing the segment $[1,1]$ . The resulting permutation is $[1,2,3,4,5]$ .