Find the product of last N nodes of the given Linked List in C++

Consider we have few elements in a linked list. We have to find the multiplication result of last n number of elements. The value of n is also given. So if the list is like [5, 7, 3, 5, 6, 9], and n = 3, then result will be 5 * 6 * 9 = 270.

The process is straight forward. We simply read the current element starting from left side, then add the elements into stack. After filling up the stack, remove n elements and multiply them with the prod. (initially prod is 1), when n number of elements are traversed, then stop.

Example

 #include<iostream> #include<stack> using namespace std;    class Node{    public:       int data;       Node *next;    };    Node* getNode(int data){       Node *newNode = new Node;       newNode->data = data;       newNode->next = NULL;       return newNode;    }    void append(struct Node** start, int key) {       Node* new_node = getNode(key);       Node *p = (*start);       if(p == NULL){          (*start) = new_node;          return;       }       while(p->next != NULL){          p = p->next;       }       p->next = new_node;    }    long long prodLastNElements(Node *start, int n) {       if(n <= 0)          return 0;       stack<int> stk;       long long res = 1;       Node* temp = start;       while (temp != NULL) {          stk.push(temp->data);          temp = temp->next;       }       while(n--){          res *= stk.top();          stk.pop();       }    return res; } int main() {    Node *start = NULL;    int arr[] = {5, 7, 3, 5, 6, 9};    int size = sizeof(arr)/sizeof(arr[0]);    int n = 3;    for(int i = 0; i<size; i++){       append(&start, arr[i]);    }    cout << "Product of last n elements: " << prodLastNElements(start, n); }

Output

Product of last n elements: 270