# Sum of smaller elements of nodes in a linked list

Given a linked list, every node of which consists of a pair of integer variables first and second to hold the data, and a pointer pointing to the next node in the list. The task is to find the sum of min(first, second) for every node.

Examples:

Input: (2, 3) -> (3, 4) – > (1, 10) -> (20, 15) -> (7, 5) -> NULL
Output: 26
2 + 3 + 1 + 15 + 5 = 26

Input: (7, 3) -> (3, 9) -> (5, 10) -> (20, 8) -> (19, 11) -> NULL
Output: 30
3 + 3 + 5 + 8 + 11 = 30

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: Traverse the whole linked list and for each node if the first element of node is smaller in comparison of second element of that node then we add first element to the variable which is holding the sum, otherwise we add the second element.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Represents node of the linked list ` `struct` `Node { ` `    ``int` `first; ` `    ``int` `second; ` `    ``Node* next; ` `}; ` ` `  `// Insertion in linked list ` `void` `insert(Node** head, ``int` `f, ``int` `s) ` `{ ` `    ``Node* ptr = *head; ` `    ``Node* temp = ``new` `Node(); ` `    ``temp->first = f; ` `    ``temp->second = s; ` `    ``temp->next = NULL; ` ` `  `    ``if` `(*head == NULL) ` `        ``*head = temp; ` `    ``else` `{ ` `        ``while` `(ptr->next != NULL) ` `            ``ptr = ptr->next; ` ` `  `        ``ptr->next = temp; ` `    ``} ` `} ` ` `  `// Function to return the required sum ` `int` `calSum(Node* head) ` `{ ` `    ``int` `sum = 0; ` `    ``while` `(head != NULL) { ` ` `  `        ``// Check for smaller element ` `        ``if` `(head->first > head->second) ` `            ``sum += head->second; ` `        ``else` `            ``sum += head->first; ` ` `  `        ``head = head->next; ` `    ``} ` `    ``return` `sum; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``Node* head = NULL; ` ` `  `    ``insert(&head, 2, 3); ` `    ``insert(&head, 3, 4); ` `    ``insert(&head, 1, 10); ` `    ``insert(&head, 20, 15); ` `    ``insert(&head, 7, 5); ` ` `  `    ``cout << calSum(head) << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of the approach ` `class` `GFG { ` `    ``// Represents node of the linked list ` `    ``static` `class` `Node { ` `        ``int` `first; ` `        ``int` `second; ` `        ``Node next; ` `    ``} ` ` `  `    ``// Insertion in linked list ` `    ``static` `Node insert(Node head, ``int` `f, ``int` `s) ` `    ``{ ` `        ``Node ptr = head; ` `        ``Node temp = ``new` `Node(); ` `        ``temp.first = f; ` `        ``temp.second = s; ` `        ``temp.next = ``null``; ` ` `  `        ``if` `(head == ``null``) ` `            ``head = temp; ` `        ``else` `{ ` `            ``while` `(ptr.next != ``null``) ` `                ``ptr = ptr.next; ` ` `  `            ``ptr.next = temp; ` `        ``} ` `        ``return` `head; ` `    ``} ` ` `  `    ``// Function to return the required sum ` `    ``static` `int` `calSum(Node head) ` `    ``{ ` `        ``int` `sum = ``0``; ` `        ``while` `(head != ``null``) { ` ` `  `            ``// Check for smaller element ` `            ``if` `(head.first > head.second) ` `                ``sum += head.second; ` `            ``else` `                ``sum += head.first; ` ` `  `            ``head = head.next; ` `        ``} ` `        ``return` `sum; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String args[]) ` `    ``{ ` `        ``Node head = ``null``; ` ` `  `        ``head = insert(head, ``2``, ``3``); ` `        ``head = insert(head, ``3``, ``4``); ` `        ``head = insert(head, ``1``, ``10``); ` `        ``head = insert(head, ``20``, ``15``); ` `        ``head = insert(head, ``7``, ``5``); ` ` `  `        ``System.out.print(calSum(head)); ` `    ``} ` `} ` ` `  `// This code is contributed by Arnab Kundu `

## Python3

 `# Python3 implementation of the approach ` ` `  `# Represents node of the linked list ` `class` `Node: ` `     `  `    ``def` `__init__(``self``, f, s): ` `        ``self``.first ``=` `f ` `        ``self``.second ``=` `s ` `        ``self``.``next` `=` `None` ` `  `# Insertion in linked list ` `def` `insert(head, f, s): ` ` `  `    ``ptr ``=` `head ` `    ``temp ``=` `Node(f, s) ` `     `  `    ``if` `head ``=``=` `None``: ` `        ``head ``=` `temp ` `    ``else``: ` `        ``while` `ptr.``next` `!``=` `None``: ` `            ``ptr ``=` `ptr.``next` ` `  `        ``ptr.``next` `=` `temp ` `         `  `    ``return` `head ` ` `  `# Function to return the required sum ` `def` `calSum(head): ` ` `  `    ``Sum` `=` `0` `    ``while` `head !``=` `None``: ` ` `  `        ``# Check for smaller element ` `        ``if` `head.first > head.second: ` `            ``Sum` `+``=` `head.second ` `        ``else``: ` `            ``Sum` `+``=` `head.first ` ` `  `        ``head ``=` `head.``next` `     `  `    ``return` `Sum` ` `  `# Driver code ` `if` `__name__ ``=``=` `"__main__"``: ` ` `  `    ``head ``=` `None` ` `  `    ``head ``=` `insert(head, ``2``, ``3``) ` `    ``head ``=` `insert(head, ``3``, ``4``) ` `    ``head ``=` `insert(head, ``1``, ``10``) ` `    ``head ``=` `insert(head, ``20``, ``15``) ` `    ``head ``=` `insert(head, ``7``, ``5``) ` ` `  `    ``print``(calSum(head)) ` `     `  `# This code is contributed by Rituraj Jain `

## C#

 `// C# implementation of the approach ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Represents node of the linked list ` `    ``public` `class` `Node { ` `        ``public` `int` `first; ` `        ``public` `int` `second; ` `        ``public` `Node next; ` `    ``} ` ` `  `    ``// Insertion in linked list ` `    ``static` `Node insert(Node head, ``int` `f, ``int` `s) ` `    ``{ ` `        ``Node ptr = head; ` `        ``Node temp = ``new` `Node(); ` `        ``temp.first = f; ` `        ``temp.second = s; ` `        ``temp.next = ``null``; ` ` `  `        ``if` `(head == ``null``) ` `            ``head = temp; ` `        ``else` `{ ` `            ``while` `(ptr.next != ``null``) ` `                ``ptr = ptr.next; ` ` `  `            ``ptr.next = temp; ` `        ``} ` `        ``return` `head; ` `    ``} ` ` `  `    ``// Function to return the required sum ` `    ``static` `int` `calSum(Node head) ` `    ``{ ` `        ``int` `sum = 0; ` `        ``while` `(head != ``null``) { ` ` `  `            ``// Check for smaller element ` `            ``if` `(head.first > head.second) ` `                ``sum += head.second; ` `            ``else` `                ``sum += head.first; ` ` `  `            ``head = head.next; ` `        ``} ` `        ``return` `sum; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main(String[] args) ` `    ``{ ` `        ``Node head = ``null``; ` ` `  `        ``head = insert(head, 2, 3); ` `        ``head = insert(head, 3, 4); ` `        ``head = insert(head, 1, 10); ` `        ``head = insert(head, 20, 15); ` `        ``head = insert(head, 7, 5); ` ` `  `        ``Console.Write(calSum(head)); ` `    ``} ` `} ` ` `  `// This code contributed by Rajput-Ji `

Output:

```26
```

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