Little Robber Girl's Zoo

题意翻译

将一个 $n$ $(1 \leq n \leq 100)$个元素的序列排成非递减序列，每次操作可以指定区间$[ L，R ]$（区间内元素个数为偶数），将区间内第一项与第二项交换，第三项与第四项交换，第五项与第六项……在 $20000$ 次内完成排序，输出每次操作。

题目描述

Little Robber Girl likes to scare animals in her zoo for fun. She decided to arrange the animals in a row in the order of non-decreasing height. However, the animals were so scared that they couldn't stay in the right places. The robber girl was angry at first, but then she decided to arrange the animals herself. She repeatedly names numbers $ l $ and $ r $ such that $ r-l+1 $ is even. After that animals that occupy positions between $ l $ and $ r $ inclusively are rearranged as follows: the animal at position $ l $ swaps places with the animal at position $ l+1 $ , the animal $ l+2 $ swaps with the animal $ l+3 $ , ..., finally, the animal at position $ r-1 $ swaps with the animal $ r $ . Help the robber girl to arrange the animals in the order of non-decreasing height. You should name at most $ 20000 $ segments, since otherwise the robber girl will become bored and will start scaring the animals again.

输入输出格式

输入格式

The first line contains a single integer $ n $ ( $ 1<=n<=100 $ ) — number of animals in the robber girl's zoo. The second line contains $ n $ space-separated integers $ a_{1},a_{2},...,a_{n} $ ( $ 1<=a_{i}<=10^{9} $ ), where $ a_{i} $ is the height of the animal occupying the $ i $ -th place.

输出格式

Print the sequence of operations that will rearrange the animals by non-decreasing height. The output should contain several lines, $ i $ -th of the lines should contain two space-separated integers $ l_{i} $ and $ r_{i} $ ( $ 1<=l_{i}&lt;r_{i}<=n $ ) — descriptions of segments the robber girl should name. The segments should be described in the order the operations are performed. The number of operations should not exceed $ 20000 $ . If the animals are arranged correctly from the start, you are allowed to output nothing.

输入输出样例

输入样例 #1

4
2 1 4 3

输出样例 #1

1 4

输入样例 #2

7
36 28 57 39 66 69 68

输出样例 #2

1 4
6 7

输入样例 #3

5
1 2 1 2 1

输出样例 #3

2 5
3 4
1 4
1 4

说明

Note that you don't have to minimize the number of operations. Any solution that performs at most $ 20000 $ operations is allowed.

题意翻译

将一个 $n$ $(1 \leq n \leq 100)$个元素的序列排成非递减序列，每次操作可以指定区间$[ L，R ]$（区间内元素个数为偶数），将区间内第一项与第二项交换，第三项与第四项交换，第五项与第六项……在 $20000$ 次内完成排序，输出每次操作。