Find Second largest element in an array | Set 2

Largest element in an Array

Last Updated : 27 Dec, 2024

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Given an array arr. The task is to find the largest element in the given array.

Examples:

Input: arr[] = [10, 20, 4]
Output: 20
Explanation: Among 10, 20 and 4, 20 is the largest.
Input: arr[] = [20, 10, 20, 4, 100]
Output: 100

Table of Content

Iterative Approach - O(n) Time and O(1) Space

The approach to solve this problem is to traverse the whole array and find the maximum among them.

C++

#include <iostream>
#include <vector>
using namespace std;

int largest(vector<int>& arr) {
    int max = arr[0];

    //Traverse  from second and compare
    // every element with current max
    for (int i = 1; i < arr.size(); i++)
        if (arr[i] > max)
            max = arr[i];

    return max;
}

int main() {
    vector<int> arr = {10, 324, 45, 90, 9808};
    cout << largest(arr);
    return 0;
}

C

#include <stdio.h>

int largest(int arr[], int n) {
    int i;
    int max = arr[0];

    // Traverse array elements from second and
    // compare every element with current max
    for (i = 1; i < n; i++)
        if (arr[i] > max)
            max = arr[i];

    return max;
}

int main() {
    int arr[] = { 10, 324, 45, 90, 9808 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    printf("%d", largest(arr, n));
    return 0;
}

Java

import java.io.*;

class GfG {
    static int largest(int[] arr) {
        int max = arr[0];

        // Traverse array elements from second and
        // compare every element with current max
        for (int i = 1; i < arr.length; i++)
            if (arr[i] > max)
                max = arr[i];

        return max;
    }

    public static void main(String[] args) {
        int arr[] = { 10, 324, 45, 90, 9808 };
        System.out.println(largest(arr));
    }
}

Python

def largest(arr, n):
    mx = arr[0]

    # Traverse array elements from second
    # and compare every element with
    # current max
    for i in range(1, n):
        if arr[i] > mx:
            mx = arr[i]

    return mx

if __name__ == '__main__':
    arr = [10, 324, 45, 90, 9808]
    n = len(arr)
    
    ans = largest(arr, n)
    
    print(ans)

C#

using System;
using System.Collections.Generic;

class GfG {
    static int Largest(List<int> arr) {
        int max = arr[0];

        // Traverse from second and compare
        // every element with current max
        for (int i = 1; i < arr.Count; i++)
            if (arr[i] > max)
                max = arr[i];

        return max;
    }

    static void Main() {
        List<int> arr = new List<int> { 10, 324, 45, 90, 9808 };
        Console.WriteLine(Largest(arr));
    }
}

JavaScript

function largest(arr) {
    let max = arr[0];

    // Traverse from second and compare
    // every element with current max
    for (let i = 1; i < arr.length; i++)
        if (arr[i] > max)
            max = arr[i];

    return max;
}

// Driver Code
const arr = [10, 324, 45, 90, 9808];
console.log(largest(arr));

Output

Recursive Approach - O(n) Time and O(n) Space

The idea is similar to the iterative approach. Here the traversal of the array is done recursively instead of an iterative loop.

C++

#include <iostream>
#include <vector>
using namespace std;

int findMax(vector<int>& arr, int i) {
  
   // Last index returns the element
    if (i == arr.size() - 1) {
        return arr[i];
    }

    // Find the maximum from the rest of the vector
    int recMax = findMax(arr, i + 1);

    // Compare with i-th element and return
    return max(recMax, arr[i]);
}

int largest(vector<int>& arr) {
  return findMax(arr,0);
}

int main() {
    vector<int> arr = {10, 324, 45, 90, 9808};
    cout << largest(arr);
    return 0;
}

C

#include <stdio.h>

int findMax(int arr[], int size, int i) {
  
    // Last index returns the element
    if (i == size - 1) {
        return arr[i];
    }

    // Find the maximum from the rest of the array
    int recMax = findMax(arr, size, i + 1);

    // Compare with i-th element and return
    return (recMax > arr[i]) ? recMax : arr[i];
}

int largest(int arr[], int size) {
    return findMax(arr, size, 0);
}

int main() {
    int arr[] = {10, 324, 45, 90, 9808};
    int size = sizeof(arr) / sizeof(arr[0]);
    printf("%d", largest(arr, size));
    return 0;
}

Java

import java.util.Arrays;

class GfG {
    static int findMax(int[] arr, int i) {
      
        // Last index returns the element
        if (i == arr.length - 1) {
            return arr[i];
        }

        // Find the maximum from the rest of the array
        int recMax = findMax(arr, i + 1);

        // Compare with i-th element and return
        return Math.max(recMax, arr[i]);
    }

    static int largest(int[] arr) {
        return findMax(arr, 0);
    }

    public static void main(String[] args) {
        int[] arr = {10, 324, 45, 90, 9808};
        System.out.println(largest(arr));
    }
}

Python

def findMax(arr, i):
  
    # Last index returns the element
    if i == len(arr) - 1:
        return arr[i]

    # Find the maximum from the rest of the list
    recMax = findMax(arr, i + 1)

    # Compare with i-th element and return
    return max(recMax, arr[i])


def largest(arr):
    return findMax(arr, 0)

if __name__ == '__main__':
  arr = [10, 324, 45, 90, 9808]
  print(largest(arr))

C#

using System;

class GfG {
    static int FindMax(int[] arr, int i) {
      
        // Last index returns the element
        if (i == arr.Length - 1) {
            return arr[i];
        }

        // Find the maximum from the rest of the array
        int recMax = FindMax(arr, i + 1);

        // Compare with i-th element and return
        return Math.Max(recMax, arr[i]);
    }

    static int Largest(int[] arr) {
        return FindMax(arr, 0);
    }

    static void Main() {
        int[] arr = {10, 324, 45, 90, 9808};
        Console.WriteLine(Largest(arr));
    }
}

JavaScript

function findMax(arr, i) {
    // Last index returns the element
    if (i === arr.length - 1) {
        return arr[i];
    }

    // Find the maximum from the rest of the array
    let recMax = findMax(arr, i + 1);

    // Compare with i-th element and return
    return Math.max(recMax, arr[i]);
}

function largest(arr) {
    return findMax(arr, 0);
}

// Driver Code
const arr = [10, 324, 45, 90, 9808];
console.log(largest(arr));

Output

Using Library Methods - O(n) Time and O(1) Space

Most of the languages have a relevant max() type in-built function to find the maximum element, such as std::max_element in C++. We can use this function to directly find the maximum element.

C++

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int largest(vector<int>& arr) {
    return *max_element(arr.begin(), arr.end());
}

int main() {
    vector<int> arr = {10, 324, 45, 90, 9808};
    cout << largest(arr);
    return 0;
}

C

#include <stdio.h>
#include <stdlib.h>

int compare(const void* a, const void* b) {
    return (*(int*)a - *(int*)b);
}

int largest(int arr[], int n) {
    qsort(arr, n, sizeof(int), compare);
    return arr[n - 1];
}

int main() {
    int arr[] = {10, 324, 45, 90, 9808};
    int n = sizeof(arr) / sizeof(arr[0]);
    printf("%d\n", largest(arr, n));
    return 0;
}

Java

import java.io.*;
import java.util.*;

class GfG {

    static int largest(int[] arr) {
        Arrays.sort(arr);
        return arr[arr.length - 1];
    }

    static public void main(String[] args) {
        int[] arr = { 10, 324, 45, 90, 9808 };
        System.out.println(largest(arr));
    }
}

Python

# Python program to find maximum in arr[] of size n 
def largest(arr):
    return max(arr)

if __name__ == '__main__':
  arr = [10, 324, 45, 90, 9808]
  print(largest(arr))

C#

using System;
using System.Linq;
using System.Collections.Generic;

class GfG {
  static int largest(List<int> arr) {
          return arr.Max();
      }
  
    static public void Main() {
 		List<int> arr = new List<int> { 10, 324, 45, 90, 9808 };
        Console.WriteLine(largest(arr));
    }
}

JavaScript

// Function to find the largest number in an array
function largest(arr) {
    return Math.max(...arr);
}

// Driver Code
const arr = [10, 324, 45, 90, 9808];
console.log(largest(arr));

Output

Find Second largest element in an array | Set 2

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