# 算法设计：未排序数组的均值和中位数的程序

2021年3月17日14:09:04 发表评论 345 次浏览

## 本文概述

``````Input  : a[] = {1, 3, 4, 2, 6, 5, 8, 7}
Output : Mean = 4.5
Median = 4.5
Sum of the elements is 1 + 3 + 4 + 2 + 6 +
5 + 8 + 7 = 36
Mean = 36/8 = 4.5
Since number of elements are even, median
is average of 4th and 5th largest elements.
which means (4 + 5)/2 = 4.5

Input  : a[] = {4, 4, 4, 4, 4}
Output : Mean = 4
Median = 4``````

{IDE}

## C ++

``````// CPP program to find mean and median of
// an array
#include <bits/stdc++.h>
using namespace std;

// Function for calculating mean
double findMean( int a[], int n)
{
int sum = 0;
for ( int i = 0; i < n; i++)
sum += a[i];

return ( double )sum / ( double )n;
}

// Function for calculating median
double findMedian( int a[], int n)
{
// First we sort the array
sort(a, a + n);

// check for even case
if (n % 2 != 0)
return ( double )a[n / 2];

return ( double )(a[(n - 1) / 2] + a[n / 2]) / 2.0;
}

// Driver code
int main()
{
int a[] = { 1, 3, 4, 2, 7, 5, 8, 6 };
int n = sizeof (a) / sizeof (a[0]);

// Function call
cout << "Mean = " << findMean(a, n) << endl;
cout << "Median = " << findMedian(a, n) << endl;
return 0;
}``````

## Java

``````// Java program to find mean
// and median of an array
import java.util.*;

class GFG
{
// Function for calculating mean
public static double findMean( int a[], int n)
{
int sum = 0 ;
for ( int i = 0 ; i < n; i++)
sum += a[i];

return ( double )sum / ( double )n;
}

// Function for calculating median
public static double findMedian( int a[], int n)
{
// First we sort the array
Arrays.sort(a);

// check for even case
if (n % 2 != 0 )
return ( double )a[n / 2 ];

return ( double )(a[(n - 1 ) / 2 ] + a[n / 2 ]) / 2.0 ;
}

// Driver code
public static void main(String args[])
{
int a[] = { 1 , 3 , 4 , 2 , 7 , 5 , 8 , 6 };
int n = a.length;

// Function call
System.out.println( "Mean = " + findMean(a, n));
System.out.println( "Median = " + findMedian(a, n));
}
}

// This article is contributed by Anshika Goyal.``````

## Python3

``````# Python3 program to find mean
# and median of an array

# Function for calculating mean

def findMean(a, n):

sum = 0
for i in range ( 0 , n):
sum + = a[i]

return float ( sum / n)

# Function for calculating median

def findMedian(a, n):

# First we sort the array
sorted (a)

# check for even case
if n % 2 ! = 0 :
return float (a[ int (n / 2 )])

return float ((a[ int ((n - 1 ) / 2 )] +
a[ int (n / 2 )]) / 2.0 )

# Driver code
a = [ 1 , 3 , 4 , 2 , 7 , 5 , 8 , 6 ]
n = len (a)

# Function call
print ( "Mean =" , findMean(a, n))
print ( "Median =" , findMedian(a, n))

# This code is contributed by Smitha Dinesh Semwal``````

## C#

``````// C# program to find mean
// and median of an array
using System;

class GFG
{
// Function for
// calculating mean
public static double findMean( int [] a, int n)
{
int sum = 0;
for ( int i = 0; i < n; i++)
sum += a[i];

return ( double )sum / ( double )n;
}

// Function for
// calculating median
public static double findMedian( int [] a, int n)
{
// First we sort
// the array
Array.Sort(a);

// check for
// even case
if (n % 2 != 0)
return ( double )a[n / 2];

return ( double )(a[(n - 1) / 2] + a[n / 2]) / 2.0;
}

// Driver Code
public static void Main()
{
int [] a = { 1, 3, 4, 2, 7, 5, 8, 6 };
int n = a.Length;

// Function call
Console.Write( "Mean = " + findMean(a, n) + "\n" );
Console.Write( "Median = " + findMedian(a, n)
+ "\n" );
}
}

// This code is contributed by Smitha .``````

## 的PHP

``````<?php
// PHP program to find mean
// and median of an array

// Function for calculating mean
function findMean(& \$a , \$n )
{
\$sum = 0;
for ( \$i = 0; \$i < \$n ; \$i ++)
\$sum += \$a [ \$i ];

return (double) \$sum /
(double) \$n ;
}

// Function for
// calculating median
function findMedian(& \$a , \$n )
{
// First we sort the array
sort( \$a );

// check for even case
if ( \$n % 2 != 0)
return (double) \$a [ \$n / 2];

return (double)( \$a [( \$n - 1) / 2] +
\$a [ \$n / 2]) / 2.0;
}

// Driver Code
\$a = array (1, 3, 4, 2, 7, 5, 8, 6);
\$n = sizeof( \$a );

// Function call
echo "Mean = " .
findMean( \$a , \$n ). "\n" ;
echo "Median = " .
findMedian( \$a , \$n );

// This code is contributed
// by ChitraNayal
?>``````

``````Mean = 4.5
Median = 4.5``````

= O(n)

Ť

ime复杂度找到中位数

= O(n Log n), 因为我们需要首先对数组进行排序。请注意, 我们可以使用讨论的方法找到O(n)时间的中位数

.