# Sum of nodes in a linked list which are greater than next node

Given a linked list, the task is to find the sum of all the nodes which are greater than the node next to them. Note that for the last node of the linked list which doesn’t have any node next to it, it must be greater than the first node in order for it to contribute to the sum.

Examples:

Input: 9 -> 2 -> 3 -> 5 -> 4 -> 6 -> 8
Output: 14
9 + 5 = 14

Input: 2 -> 1 -> 5 -> 7
Output: 9
2 + 7 = 9

## 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 node is greater than the next node then add it to the sum. For the last node, compare it to the head of the linked list, if last node is greater than the head then add it to the sum. Print the sum in the end.

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` `data; ` `    ``Node* next; ` `}; ` ` `  `// Function to insert a node at the ` `// end of the linked list ` `void` `insert(Node** root, ``int` `item) ` `{ ` `    ``Node *ptr = *root, *temp = ``new` `Node; ` `    ``temp->data = item; ` `    ``temp->next = NULL; ` ` `  `    ``if` `(*root == NULL) ` `        ``*root = temp; ` `    ``else` `{ ` `        ``while` `(ptr->next != NULL) ` `            ``ptr = ptr->next; ` `        ``ptr->next = temp; ` `    ``} ` `} ` ` `  `// Function to return the sum of the nodes ` `// which are greater than the node next to them ` `int` `sum(Node* root) ` `{ ` ` `  `    ``// If there are no nodes ` `    ``if` `(root == NULL) ` `        ``return` `0; ` ` `  `    ``int` `sm = 0; ` `    ``Node* ptr = root; ` `    ``while` `(ptr->next != NULL) { ` ` `  `        ``// If the node is greater than the next node ` `        ``if` `(ptr->data > ptr->next->data) ` `            ``sm += ptr->data; ` `        ``ptr = ptr->next; ` `    ``} ` ` `  `    ``// For the last node ` `    ``if` `(ptr->data > root->data) ` `        ``sm += ptr->data; ` ` `  `    ``// Return the sum ` `    ``return` `sm; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``Node* root = NULL; ` ` `  `    ``insert(&root, 9); ` `    ``insert(&root, 2); ` `    ``insert(&root, 3); ` `    ``insert(&root, 5); ` `    ``insert(&root, 4); ` `    ``insert(&root, 6); ` `    ``insert(&root, 8); ` ` `  `    ``cout << sum(root) << endl; ` `    ``return` `0; ` `} `

## Java

 `// Java implementation of the approach  ` `class` `GFG ` `{ ` ` `  `// Represents node of the linked list  ` `static` `class` `Node  ` `{  ` `    ``int` `data;  ` `    ``Node next;  ` `};  ` ` `  `// Function to insert a node at the  ` `// end of the linked list  ` `static` `Node insert(Node root, ``int` `item)  ` `{  ` `    ``Node ptr = root, temp = ``new` `Node();  ` `    ``temp.data = item;  ` `    ``temp.next = ``null``;  ` ` `  `    ``if` `(root == ``null``)  ` `        ``root = temp;  ` `    ``else`  `    ``{  ` `        ``while` `(ptr.next != ``null``)  ` `            ``ptr = ptr.next;  ` `        ``ptr.next = temp;  ` `    ``}  ` `    ``return` `root; ` `}  ` ` `  `// Function to return the sum of the nodes  ` `// which are greater than the node next to them  ` `static` `int` `sum(Node root)  ` `{  ` ` `  `    ``// If there are no nodes  ` `    ``if` `(root == ``null``)  ` `        ``return` `0``;  ` ` `  `    ``int` `sm = ``0``;  ` `    ``Node ptr = root;  ` `    ``while` `(ptr.next != ``null``)  ` `    ``{  ` ` `  `        ``// If the node is greater than the next node  ` `        ``if` `(ptr.data > ptr.next.data)  ` `            ``sm += ptr.data;  ` `        ``ptr = ptr.next;  ` `    ``}  ` ` `  `    ``// For the last node  ` `    ``if` `(ptr.data > root.data)  ` `        ``sm += ptr.data;  ` ` `  `    ``// Return the sum  ` `    ``return` `sm;  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `main(String args[]) ` `{  ` `    ``Node root = ``null``;  ` ` `  `    ``root=insert(root, ``9``);  ` `    ``root=insert(root, ``2``);  ` `    ``root=insert(root, ``3``);  ` `    ``root=insert(root, ``5``);  ` `    ``root=insert(root, ``4``);  ` `    ``root=insert(root, ``6``);  ` `    ``root=insert(root, ``8``);  ` ` `  `    ``System.out.print( sum(root) ); ` `} ` `}  ` ` `  `// This code is contributed by Arnab Kundu `

## Python3

 `# Python3 implementation of the approach ` `import` `math ` ` `  `# Represents node of the linked list ` `class` `Node:  ` `    ``def` `__init__(``self``, data):  ` `        ``self``.data ``=` `data  ` `        ``self``.``next` `=` `None` ` `  `# Function to root=insert a node at the ` `# end of the linked list ` `def` `insert(root, item): ` ` `  `    ``ptr ``=` `root ` `    ``temp ``=` `Node(item); ` `    ``temp.data ``=` `item; ` `    ``temp.``next` `=` `None``; ` `     `  `    ``if` `(root ``=``=` `None``): ` `        ``root ``=` `temp; ` `    ``else``: ` `        ``while` `(ptr.``next` `!``=` `None``): ` `            ``ptr ``=` `ptr.``next``; ` `        ``ptr.``next` `=` `temp; ` `     `  `    ``return` `root ` ` `  `# Function to return the sum of the nodes ` `# which are greater than the node next to them ` `def` `sum``(root): ` ` `  `    ``# If there are no nodes ` `    ``if` `(root ``=``=` `None``): ` `        ``return` `0``; ` ` `  `    ``sm ``=` `0``; ` `    ``ptr ``=` `root; ` `    ``while` `(ptr.``next` `!``=` `None``): ` ` `  `        ``# If the node is greater than the next node ` `        ``if` `(ptr.data > ptr.``next``.data): ` `            ``sm ``+``=` `ptr.data; ` `        ``ptr ``=` `ptr.``next``; ` ` `  `    ``# For the last node ` `    ``if` `(ptr.data > root.data): ` `        ``sm ``+``=` `ptr.data; ` ` `  `    ``# Return the sum ` `    ``return` `sm; ` ` `  `# Driver code ` `if` `__name__``=``=``'__main__'``:  ` `    ``root ``=` `None``; ` `    ``root ``=` `insert(root, ``9``); ` `    ``root ``=` `insert(root, ``2``); ` `    ``root ``=` `insert(root, ``3``); ` `    ``root ``=` `insert(root, ``5``); ` `    ``root ``=` `insert(root, ``4``); ` `    ``root ``=` `insert(root, ``6``); ` `    ``root ``=` `insert(root, ``8``); ` ` `  `    ``print``(``sum``(root)) ` `     `  `# This code is contributed by Srathore `

## C#

 `// C# implementation of the approach ` `using` `System; ` ` `  `class` `GFG ` `{ ` ` `  `// Represents node of the linked list  ` `public` `class` `Node  ` `{  ` `    ``public` `int` `data;  ` `    ``public` `Node next;  ` `};  ` ` `  `// Function to insert a node at the  ` `// end of the linked list  ` `static` `Node insert(Node root, ``int` `item)  ` `{  ` `    ``Node ptr = root, temp = ``new` `Node();  ` `    ``temp.data = item;  ` `    ``temp.next = ``null``;  ` ` `  `    ``if` `(root == ``null``)  ` `        ``root = temp;  ` `    ``else` `    ``{  ` `        ``while` `(ptr.next != ``null``)  ` `            ``ptr = ptr.next;  ` `        ``ptr.next = temp;  ` `    ``}  ` `    ``return` `root; ` `}  ` ` `  `// Function to return the sum of the nodes  ` `// which are greater than the node next to them  ` `static` `int` `sum(Node root)  ` `{  ` ` `  `    ``// If there are no nodes  ` `    ``if` `(root == ``null``)  ` `        ``return` `0;  ` ` `  `    ``int` `sm = 0;  ` `    ``Node ptr = root;  ` `    ``while` `(ptr.next != ``null``)  ` `    ``{  ` ` `  `        ``// If the node is greater than the next node  ` `        ``if` `(ptr.data > ptr.next.data)  ` `            ``sm += ptr.data;  ` `        ``ptr = ptr.next;  ` `    ``}  ` ` `  `    ``// For the last node  ` `    ``if` `(ptr.data > root.data)  ` `        ``sm += ptr.data;  ` ` `  `    ``// Return the sum  ` `    ``return` `sm;  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `Main(String []args) ` `{  ` `    ``Node root = ``null``;  ` ` `  `    ``root = insert(root, 9);  ` `    ``root = insert(root, 2);  ` `    ``root = insert(root, 3);  ` `    ``root = insert(root, 5);  ` `    ``root = insert(root, 4);  ` `    ``root = insert(root, 6);  ` `    ``root = insert(root, 8);  ` ` `  `    ``Console.Write( sum(root) ); ` `} ` `} ` ` `  `// This code contributed by Rajput-Ji `

Output:

```14
```

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