Restore the Permutation by Merger

题意翻译

给定一个长度为 $2n$ 的数组 $a$，求长度为 $n$ 数组 $p$ 满足 $p$ 中的数为 $1$~$n$，且数组 $a$ 可以由两个数组 $p$ 组合得到。 这里两个数组组合指的是第二个数组的每个元素按顺序插入第一个数组的任意空中。例如两个 $p=[3,1,2]$ 可以组合成 $[3,1,2,3,1,2], [3,3,1,1,2,2], [3,1,3,1,2,2]$，但不能组合成 $[1,3,2,1,2,3], [3,1,2,3,2,1], [3,3,1,2,2,1]$。 给定 $n$ 和长度为 $2n$ 的数组 $a$，求满足要求的数组 $p$，保证唯一解。

题目描述

A permutation of length $ n $ is a sequence of integers from $ 1 $ to $ n $ of length $ n $ containing each number exactly once. For example, $ [1] $ , $ [4, 3, 5, 1, 2] $ , $ [3, 2, 1] $ are permutations, and $ [1, 1] $ , $ [0, 1] $ , $ [2, 2, 1, 4] $ are not. There was a permutation $ p[1 \dots n] $ . It was merged with itself. In other words, let's take two instances of $ p $ and insert elements of the second $ p $ into the first maintaining relative order of elements. The result is a sequence of the length $ 2n $ . For example, if $ p=[3, 1, 2] $ some possible results are: $ [3, 1, 2, 3, 1, 2] $ , $ [3, 3, 1, 1, 2, 2] $ , $ [3, 1, 3, 1, 2, 2] $ . The following sequences are not possible results of a merging: $ [1, 3, 2, 1, 2, 3 $ \], \[ $ 3, 1, 2, 3, 2, 1] $ , $ [3, 3, 1, 2, 2, 1] $ . For example, if $ p=[2, 1] $ the possible results are: $ [2, 2, 1, 1] $ , $ [2, 1, 2, 1] $ . The following sequences are not possible results of a merging: $ [1, 1, 2, 2 $ \], \[ $ 2, 1, 1, 2] $ , $ [1, 2, 2, 1] $ . Your task is to restore the permutation $ p $ by the given resulting sequence $ a $ . It is guaranteed that the answer exists and is unique. You have to answer $ t $ independent test cases.

输入输出格式

输入格式

The first line of the input contains one integer $ t $ ( $ 1 \le t \le 400 $ ) — the number of test cases. Then $ t $ test cases follow. The first line of the test case contains one integer $ n $ ( $ 1 \le n \le 50 $ ) — the length of permutation. The second line of the test case contains $ 2n $ integers $ a_1, a_2, \dots, a_{2n} $ ( $ 1 \le a_i \le n $ ), where $ a_i $ is the $ i $ -th element of $ a $ . It is guaranteed that the array $ a $ represents the result of merging of some permutation $ p $ with the same permutation $ p $ .

输出格式

For each test case, print the answer: $ n $ integers $ p_1, p_2, \dots, p_n $ ( $ 1 \le p_i \le n $ ), representing the initial permutation. It is guaranteed that the answer exists and is unique.

输入输出样例

输入样例 #1

5
2
1 1 2 2
4
1 3 1 4 3 4 2 2
5
1 2 1 2 3 4 3 5 4 5
3
1 2 3 1 2 3
4
2 3 2 4 1 3 4 1

输出样例 #1

1 2 
1 3 4 2 
1 2 3 4 5 
1 2 3 
2 3 4 1