Find the missing integer in an array if mean is given
Last Updated :
20 Feb, 2023
Given an array of size N-1 and the mean of N elements (one element is not given). We need to find the missing value X in the array.
Examples:
Input : a[] = {2, 4, 20}, Mean = 9
Output : Missing Element = 10
Explanation : Mean of (2, 4, 20, 10) is (2 + 4 + 20 + 10)/4 = 9
Let x be the missing element
Mean = (a1 + a2 + a3.. + X + ..an)/N.
So (a1 + a2 + a3.. + X + ..aN) = Mean*N .
Missing element x = (Mean*N - (a1 + a2 + a3....aN))
Implementation:
C++
#include <bits/stdc++.h>
using namespace std;
int findMissing( int a[], int N, int mean)
{
int sum = 0;
for ( int i = 0; i < N - 1; i++)
sum += a[i];
return (mean * N) - sum;
}
int main() {
int a[] = {25, 65, 80};
int mean = 50;
int n = sizeof (a)/ sizeof (a[0]);
cout << "The missing element : "
<< findMissing(a, n+1, mean) << endl;
return 0;
}
|
Java
import java.io.*;
class GFG
{
public static int findMissing( int a[], int N, int mean)
{
int sum = 0 ;
for ( int i = 0 ; i < N - 1 ; i++)
sum += a[i];
return (mean * N) - sum;
}
public static void main (String[] args)
{
int a[] = { 25 , 65 , 80 };
int mean = 50 ;
int n = a.length;
System.out.println( "The missing element : "
+ findMissing(a, n + 1 , mean));
}
}
|
Python3
def findMissing( a , N , mean ):
sum = 0
for i in range (N - 1 ):
sum + = a[i]
return (mean * N) - sum
a = [ 25 , 65 , 80 ]
mean = 50
n = len (a)
print ( "The missing element : " , end = '')
print (findMissing(a, n + 1 , mean))
|
C#
using System;
class GFG {
public static int findMissing( int [] a, int N, int mean)
{
int sum = 0;
for ( int i = 0; i < N - 1; i++)
sum += a[i];
return (mean * N) - sum;
}
public static void Main()
{
int [] a = { 25, 65, 80 };
int mean = 50;
int n = a.Length;
Console.WriteLine( "The missing element : "
+ findMissing(a, n + 1, mean));
}
}
|
PHP
<?php
function findMissing( $a , $N , $mean )
{
$sum = 0;
for ( $i = 0; $i < $N - 1; $i ++)
$sum += $a [ $i ];
return ( $mean * $N ) - $sum ;
}
$a = array (25, 65, 80);
$mean = 50;
$n = count ( $a );
echo "The missing element : "
.findMissing( $a , $n + 1, $mean );
?>
|
Javascript
<script>
function findMissing( a, N, mean)
{
let sum = 0;
for (let i = 0; i < N - 1; i++)
sum += a[i];
return (mean * N) - sum;
}
let a = [25, 65, 80];
let mean = 50;
let n = a.length;
document.write( "The missing element : "
+ findMissing(a, n+1, mean) + "</br>" );
</script>
|
Output
The missing element : 30
Time complexity: O(N) where N is no of the elements in the given array.
Auxiliary space: O(1) since constant space is required.
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