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Find element in a sorted array whose frequency is greater than or equal to n/2.
  • Difficulty Level : Easy
  • Last Updated : 15 Apr, 2021

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].
 

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>

Output: 

2

Time Complexity : O(1)
Related Articles : 
Majority element in an unsorted array 
Check for majority element in a sorted array
This article is contributed by Amit Kumar. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 




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