本文概述
数组的平均值=(所有元素的总和)/(元素数量)
中位数
当n为奇数时, 大小为n的排序数组的定义为中间元素, 而当n为偶数时, 定义为中间两个元素的平均值。
由于此处未对数组进行排序, 因此我们首先对数组进行排序, 然后应用上述公式。
例子:
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
推荐:请尝试以下方法
{IDE}
首先, 在继续解决方案之前。
下面是代码实现:
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
?>
输出如下
Mean = 4.5
Median = 4.5
时间复杂度求平均值
= 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
这里
和
这里
.