Find the missing integer in an array if mean is given
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++
// C++ program to find missing element in a // given array from mean. #include <bits/stdc++.h> using namespace std; // Size of a[] is N - 1 (one element missing) int findMissing( int a[], int N, int mean) { // Find sum of array elements 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
// Java program to find missing element // in a given array from mean. import java.io.*; class GFG { // Size of a[] is N - 1 (one element missing) public static int findMissing( int a[], int N, int mean) { // Find sum of array elements int sum = 0 ; for ( int i = 0 ; i < N - 1 ; i++) sum += a[i]; return (mean * N) - sum; } // Driver code 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)); } } // This code is contributed by upendra bartwal |
Python3
# Python3 code to find missing element # in a given array from mean. # Size of a[] is N - 1 # (one element missing) def findMissing( a , N , mean ): # Find sum of array elements sum = 0 for i in range (N - 1 ): sum + = a[i] return (mean * N) - sum # Driver Code a = [ 25 , 65 , 80 ] mean = 50 n = len (a) print ( "The missing element : " , end = '') print (findMissing(a, n + 1 , mean)) # This code is contributed by Sharad Bhardwaj. |
C#
// C# program to find missing element // in a given array from mean. using System; class GFG { // Size of a[] is N - 1 // (one element missing) public static int findMissing( int [] a, int N, int mean) { // Find sum of array elements int sum = 0; for ( int i = 0; i < N - 1; i++) sum += a[i]; return (mean * N) - sum; } // Driver code 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)); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to find missing // element in a given array // from mean. // Size of a[] is N - 1 // (one element missing) function findMissing( $a , $N , $mean ) { // Find sum of array elements $sum = 0; for ( $i = 0; $i < $N - 1; $i ++) $sum += $a [ $i ]; return ( $mean * $N ) - $sum ; } // Driver Code $a = array (25, 65, 80); $mean = 50; $n = count ( $a ); echo "The missing element : " .findMissing( $a , $n + 1, $mean ); // This code is contributed by Sam007 ?> |
Javascript
<script> // Javascript program to find // missing element in a // given array from mean. // Size of a[] is N - 1 // (one element missing) function findMissing( a, N, mean) { // Find sum of array elements let sum = 0; for (let i = 0; i < N - 1; i++) sum += a[i]; return (mean * N) - sum; } // Driver Code 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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