Find element in a sorted array whose frequency is greater than or equal to n/2.

Last Updated : 24 Mar, 2023

Given a sorted array of length n, find the number in array that appears more than or equal to n/2 times. It is given that such element always exists.

Examples:

Input :  2 3 3 4  Output : 3    Input :  3 4 5 5 5   Output : 5    Input : 1 1 1 2 3  Output : 1

To find that number, we traverse the array and check the frequency of every element in array if it is greater than or equals to n/2 but it requires extra space and time complexity will be O(n).

But we can see that the if there is number that comes more than or equal to n/2 times in a sorted array, then that number must be present at the position n/2 i.e. a[n/2].

Implementation:

C++

   // C++ code to find majority element in a 
// sorted array 
#include <iostream> 
using namespace std; 
  
int findMajority(int arr[], int n) 
{ 
    return arr[n / 2]; 
} 
  
int main() 
{ 
    int arr[] = { 1, 2, 2, 3 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
    cout << findMajority(arr, n); 
    return 0; 
} 
 
  

Java

   // Java code to find majority element in a 
// sorted array 
public class Test { 
  
    public static int findMajority(int arr[], int n) 
    { 
        return arr[n / 2]; 
    } 
    public static void main(String args[]) 
    { 
        int arr[] = { 1, 2, 2, 3 }; 
        int n = arr.length; 
        System.out.println(findMajority(arr, n)); 
    } 
} 
 
  

Python 3

   # Python 3 code to find 
# majority element in a 
# sorted array 
  
def findMajority(arr, n): 
  
    return arr[int(n / 2)] 
  
# Driver Code 
arr = [1, 2, 2, 3] 
n = len(arr)  
print(findMajority(arr, n)) 
  
# This code is contributed by Smitha. 
 
  

C#

   // C# code to find majority element in a 
// sorted array 
using System; 
  
public class GFG { 
  
    public static int findMajority(int []arr, int n) 
    { 
        return arr[n / 2]; 
    } 
      
    // Driver code 
    public static void Main() 
    { 
          
        int []arr = { 1, 2, 2, 3 }; 
        int n = arr.Length; 
          
        Console.WriteLine(findMajority(arr, n)); 
    } 
} 
  
// This code is contributed by vt_m.  
 
  

PHP

   <?php 
// PHP code to find majority  
// element in a sorted array 
  
function findMajority($arr, $n) 
{ 
    return $arr[intval($n / 2)]; 
} 
  
    // Driver Code 
    $arr = array(1, 2, 2, 3); 
    $n = count($arr); 
    echo findMajority($arr, $n);      
      
// This code is contributed by Sam007 
?> 
 
  

Javascript

   <script> 
  
// Javascript code to find majority element in a 
// sorted array 
  
function findMajority(arr,  n) 
{ 
    return arr[(Math.floor(n / 2))]; 
} 
  
// driver code  
  
    let arr = [ 1, 2, 2, 3 ]; 
    let n = arr.length; 
    document.write(findMajority(arr, n)); 
  
</script>
 
  