# Find the largest and second largest value in a Linked List

Given a Linked List, the task is to find the largest and second largest value in a Linked List.
Example:

Input: LL = 10 -> 15 -> 5 -> 20 -> 7 -> 9
Output:
Largest = 20
Second Largest = 15
Input: LL = 0 -> 5 -> 52 -> 21
Output:
Largest = 52
Second Largest = 21

Approach:

1. Store the maximum of first two nodes in a variable max.
2. Store the minimum of first two nodes in a variable second_max.
3. Iterate over the remaining linked list. For each node:
• If current node value is greater than max, then set second_max as max and max as current node’s value.
• Else if current node value is greater than second_max, then set second_max as current node’s value.

Below is the implementation of the above approach:

## C++

 `// C++ program to find the largest and` `// second largest element in a Linked List`   `#include ` `using` `namespace` `std;`   `// Link list node` `struct` `Node {` `    ``int` `data;` `    ``struct` `Node* next;` `};`   `// Function to push the node at the` `// beginning of the linked list` `void` `push(``struct` `Node** head_ref,` `          ``int` `new_data)` `{` `    ``struct` `Node* new_node` `        ``= (``struct` `Node*)``malloc``(` `            ``sizeof``(``struct` `Node));`   `    ``new_node->data = new_data;` `    ``new_node->next = (*head_ref);` `    ``(*head_ref) = new_node;` `}`   `// Function to print the largest` `// and second largest element` `void` `findLargestAndSecondLargest(``struct` `Node* head)` `{` `    ``// initialise max and second max using` `    ``// first two nodes of linked list` `    ``int` `val1 = head->data,` `        ``val2 = head->next->data,` `        ``max = std::max(val1, val2),` `        ``second_max = std::min(val1, val2);`   `    ``// move the head pointer to 3rd node` `    ``head = head->next->next;`   `    ``// iterate over rest of linked list` `    ``while` `(head != NULL) {`   `        ``if` `(head->data > max) {`   `            ``// If current node value is greater` `            ``// than max, then set second_max as` `            ``// current max value and max as` `            ``// current node value` `            ``second_max = max;` `            ``max = head->data;` `        ``}` `        ``else` `if` `(head->data > second_max) {`   `            ``// else if current node value is` `            ``// greater than second_max, set` `            ``// second_max as node value` `            ``second_max = head->data;` `        ``}`   `        ``// move the head pointer to next node` `        ``head = head->next;` `    ``}`   `    ``// Print the largest` `    ``// and second largest value` `    ``cout << ``"Largest = "` `         ``<< max << endl;` `    ``cout << ``"Second Largest = "` `         ``<< second_max << endl;` `}`   `// Driver code` `int` `main()` `{` `    ``struct` `Node* head = NULL;`   `    ``push(&head, 20);` `    ``push(&head, 5);` `    ``push(&head, 15);` `    ``push(&head, 10);` `    ``push(&head, 7);` `    ``push(&head, 6);` `    ``push(&head, 11);` `    ``push(&head, 9);`   `    ``findLargestAndSecondLargest(head);`   `    ``return` `0;` `}`

## Java

 `// Java program to find the largest and` `// second largest element in a Linked List` `class` `GFG{` ` `  `// Link list node` `static` `class` `Node {` `    ``int` `data;` `    ``Node next;`   `};` ` `  `// Function to push the node at the` `// beginning of the linked list` `static` `Node push(Node head_ref,` `          ``int` `new_data)` `{` `    ``Node new_node` `        ``= ``new` `Node();` ` `  `    ``new_node.data = new_data;` `    ``new_node.next = head_ref;` `    ``head_ref = new_node;` `    ``return` `head_ref;` `}` ` `  `// Function to print the largest` `// and second largest element` `static` `void` `findLargestAndSecondLargest(Node head)` `{` `    ``// initialise max and second max using` `    ``// first two nodes of linked list` `    ``int` `val1 = head.data,` `        ``val2 = head.next.data,` `        ``max = Math.max(val1, val2),` `        ``second_max = Math.min(val1, val2);` ` `  `    ``// move the head pointer to 3rd node` `    ``head = head.next.next;` ` `  `    ``// iterate over rest of linked list` `    ``while` `(head != ``null``) {` ` `  `        ``if` `(head.data > max) {` ` `  `            ``// If current node value is greater` `            ``// than max, then set second_max as` `            ``// current max value and max as` `            ``// current node value` `            ``second_max = max;` `            ``max = head.data;` `        ``}` `        ``else` `if` `(head.data > second_max) {` ` `  `            ``// else if current node value is` `            ``// greater than second_max, set` `            ``// second_max as node value` `            ``second_max = head.data;` `        ``}` ` `  `        ``// move the head pointer to next node` `        ``head = head.next;` `    ``}` ` `  `    ``// Print the largest` `    ``// and second largest value` `    ``System.out.print(``"Largest = "` `         ``+ max +``"\n"``);` `    ``System.out.print(``"Second Largest = "` `         ``+ second_max +``"\n"``);` `}` ` `  `// Driver code` `public` `static` `void` `main(String[] args)` `{` `    ``Node head = ``null``;` ` `  `    ``head = push(head, ``20``);` `    ``head = push(head, ``5``);` `    ``head = push(head, ``15``);` `    ``head = push(head, ``10``);` `    ``head = push(head, ``7``);` `    ``head = push(head, ``6``);` `    ``head = push(head, ``11``);` `    ``head = push(head, ``9``);` ` `  `    ``findLargestAndSecondLargest(head);` `}` `}`   `// This code is contributed by Rajput-Ji`

## Python3

 `# Python3 program to find the largest and` `# second largest element in a Linked List` `# Node class ` `class` `Node: ` `    `  `    ``# Function to initialize the node object ` `    ``def` `__init__(``self``, data): ` `        `  `        ``# Assign data ` `        ``self``.data ``=` `data ` `        `  `        ``# Initialize ` `        ``# next as null` `        ``self``.``next` `=` `None` `    `  `# Linked List Class` `class` `LinkedList:`   `    ``# Function to initialize the` `    ``# LinkedList class.` `    ``def` `__init__(``self``): ` `        `  `        ``# Initialize head as None ` `        ``self``.head ``=` `None`   `    ``# This function insert a new node at the ` `    ``# beginning of the linked list ` `    ``def` `push(``self``, new_data): ` `    `  `        ``# Create a new Node ` `        ``new_node ``=` `Node(new_data) `   `        ``# Make next of new Node as head ` `        ``new_node.``next` `=` `self``.head `   `        ``# Move the head to point to new Node ` `        ``self``.head ``=` `new_node`   `    ``# Function to find the max and` `    ``# second largest value from the list` `    ``def` `findLargestAndSecondLargest(``self``):`   `        ``# Take a Head to iterate list` `        ``Head ``=` `self``.head`   `        ``# Initialize max and second_max` `        ``# using first two nodes of the list` `        ``val1 ``=` `Head.data` `        ``val2 ``=` `Head.``next``.data` `        ``Max` `=` `max``(val1, val2)` `        ``second_max ``=` `min``(val1, val2)`   `        ``# Move the Head to third node` `        ``Head ``=` `Head.``next``.``next`   `        ``# Iterate over rest of linked list` `        ``while``(Head !``=` `None``):`   `            ``# If current node value is ` `            ``# greater then Max then` `            ``if``(Head.data > ``Max``):`   `                ``# Set the current max to second_max` `                ``# and current node value to max` `                ``second_max ``=` `Max` `                ``Max` `=` `Head.data`   `            ``# Else if current node value is` `            ``# greater then second_max value` `            ``elif``(Head.data > second_max):`   `                ``# Then current node value` `                ``# to second_max` `                ``second_max ``=` `Head.data`   `            ``# Move the head to next node` `            ``Head ``=` `Head.``next`   `        ``# Print the largest and second largest values` `        ``print``(``"Largest = "``, ``Max``)` `        ``print``(``"Second Largest = "``, second_max)`   `# Driver code` `if` `__name__ ``=``=` `'__main__'``:`   `    ``# Initialising the linked list` `    ``head ``=` `LinkedList()`   `    ``# Pushing the values in list` `    ``head.push(``20``)` `    ``head.push(``5``)` `    ``head.push(``15``)` `    ``head.push(``10``)` `    ``head.push(``7``)` `    ``head.push(``6``)` `    ``head.push(``11``)` `    ``head.push(``9``)` `    `  `    ``# Calling the function to print` `    ``# largest and second largest values.` `    ``head.findLargestAndSecondLargest()` `            `  `# This code is contributed by Amit Mangal.`

## C#

 `// C# program to find the largest and` `// second largest element in a Linked List` `using` `System;`   `class` `GFG{` `  `  `// Link list node` `class` `Node {` `    ``public` `int` `data;` `    ``public` `Node next;` ` `  `};` `  `  `// Function to push the node at the` `// beginning of the linked list` `static` `Node push(Node head_ref,` `          ``int` `new_data)` `{` `    ``Node new_node` `        ``= ``new` `Node();` `  `  `    ``new_node.data = new_data;` `    ``new_node.next = head_ref;` `    ``head_ref = new_node;` `    ``return` `head_ref;` `}` `  `  `// Function to print the largest` `// and second largest element` `static` `void` `findLargestAndSecondLargest(Node head)` `{` `    ``// initialise max and second max using` `    ``// first two nodes of linked list` `    ``int` `val1 = head.data,` `        ``val2 = head.next.data,` `        ``max = Math.Max(val1, val2),` `        ``second_max = Math.Min(val1, val2);` `  `  `    ``// move the head pointer to 3rd node` `    ``head = head.next.next;` `  `  `    ``// iterate over rest of linked list` `    ``while` `(head != ``null``) {` `  `  `        ``if` `(head.data > max) {` `  `  `            ``// If current node value is greater` `            ``// than max, then set second_max as` `            ``// current max value and max as` `            ``// current node value` `            ``second_max = max;` `            ``max = head.data;` `        ``}` `        ``else` `if` `(head.data > second_max) {` `  `  `            ``// else if current node value is` `            ``// greater than second_max, set` `            ``// second_max as node value` `            ``second_max = head.data;` `        ``}` `  `  `        ``// move the head pointer to next node` `        ``head = head.next;` `    ``}` `  `  `    ``// Print the largest` `    ``// and second largest value` `    ``Console.Write(``"Largest = "` `         ``+ max +``"\n"``);` `    ``Console.Write(``"Second Largest = "` `         ``+ second_max +``"\n"``);` `}` `  `  `// Driver code` `public` `static` `void` `Main(String[] args)` `{` `    ``Node head = ``null``;` `  `  `    ``head = push(head, 20);` `    ``head = push(head, 5);` `    ``head = push(head, 15);` `    ``head = push(head, 10);` `    ``head = push(head, 7);` `    ``head = push(head, 6);` `    ``head = push(head, 11);` `    ``head = push(head, 9);` `  `  `    ``findLargestAndSecondLargest(head);` `}` `}`   `// This code is contributed by Princi Singh`

## Javascript

 ``

Output:

```Largest = 20
Second Largest = 15```

Performance Analysis

• Time Complexity: In the above approach, as we are iterating over the linked list only once, so the time complexity is O(N).
• Auxiliary Space Complexity: In the above approach, we are not using any extra space apart from a few constant size variables, so Auxiliary space complexity is O(1).

Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!

Previous
Next