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C++ Program to find largest element in an array

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  • Last Updated : 18 Oct, 2022
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Given an array arr of size N, the task is to find the largest element in the given array. 

Example: 

Input: arr[] = {10, 20, 4}
Output: 20

Input : arr[] = {20, 10, 20, 4, 100}
Output : 100

Approach 1 – Linear Traversal: One of the most simplest and basic approach to solve this problem is to simply traverse the whole list and find the maximum among them. 

Follow the steps below to implement this idea:

  • Create a local variable max to store the maximum among the list
  • Initialize max with the first element initially, to start the comparison.
  • Then traverse the given array from second element till end, and for each element:
    • Compare the current element with max
    • If the current element is greater than max, then replace the value of max with the current element.
  • At the end, return and print the value of the largest element of array stored in max.

Below is the implementation of the above approach: 

CPP




// C++ program to find maximum
// in arr[] of size n 
#include <bits/stdc++.h>
using namespace std;
  
int largest(int arr[], int n)
{
    int i;
      
    // Initialize maximum element
    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;
}
  
// Driver Code
int main()
{
    int arr[] = {10, 324, 45, 90, 9808};
    int n = sizeof(arr) / sizeof(arr[0]);
    cout << "Largest in given array is " << 
             largest(arr, n);
    return 0;
}
  
// This Code is contributed by Shivi_Aggarwal


Output:

Largest in given array is 9808

Time complexity: O(N), to traverse the Array completely.
Auxiliary Space: O(1), as only an extra variable is created, which will take O(1) space.

Approach 2: Using Library Function: 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.  

Below is the implementation of the above approach: 

C++




// C++ program to find maximum 
// in arr[] of size n 
#include <bits/stdc++.h>
using namespace std;
  
// Returns maximum in arr[] 
// of size n
int largest(int arr[], int n)
{
    return *max_element(arr, arr+n);
}
  
// Driver code
int main()
{
    int arr[] = {10, 324, 45, 90, 9808};
    int n = sizeof(arr)/sizeof(arr[0]);
    cout << largest(arr, n);
    return 0;
}


Output

9808

Time complexity: O(N), since the in-built max_element() function takes O(N) time.
Auxiliary Space: O(1), as only an extra variable is created, which will take O(1) space.


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