1625:Sequence Median(翻译）

Jormungand_1

于 2022-02-07 20:54:28 发布

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分类专栏：寒假英文题翻译文章标签：排序算法算法

本文链接：https://blog.youkuaiyun.com/m0_63535901/article/details/122814477

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该博客讨论了如何找到一个包含N个非负整数的序列的中位数。当N为奇数时，中位数是排序后的中间元素；当N为偶数时，它是中间两个数的平均值。程序需要处理未排序的序列，输入长度在1到250000之间，每个元素不超过2^32-1。输出要求保留一位小数。

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http://noi.openjudge.cn/ch0401/1625/

描述

Given a sequence of N nonnegative integers. Let's define the median of such sequence. If N is odd the median is the element with stands in the middle of the sequence after it is sorted. One may notice that in this case the median has position (N+1)/2 in sorted sequence if sequence elements are numbered starting with 1. If N is even then the median is the semi-sum of the two "middle" elements of sorted sequence. I.e. semi-sum of the elements in positions N/2 and (N/2)+1 of sorted sequence. But original sequence might be unsorted.

给一个n个非负数的序列。我们这样定义序列的中值。如果N是奇数，那么序列的中位数是序列排序后中间的数。一个注意到的地方是如果序列从一开始编号，那么在这种情况下的中位数是序列排序后编号为（n+1）/2的值。如果N是偶数，序列的中位数是序列排序后中间两个数的平均数。但原序列可能没被排序。

Your task is to write program to find the median of given sequence.

你的任务是写一个程序找到给定序列的中位数

输入

The first line of input contains the only integer number N - the length of the sequence. Sequence itself follows in subsequent lines, one number in a line. The length of the sequence lies in the range from 1 to 250000. Each element of the sequence is a positive integer not greater than 2^32 - 1 inclusive.

第一行只输入一个整数N 序列的长度。序列在后面的行中，一个数字一行。序列的长度在1到250000之间。每一个元素都是不超过2^32的-1的正整数

输出

You should print the value of the median with exactly one digit after decimal point.

你应该输出保留小数点后一位的中位数