• Last Updated : 06 Jan, 2022

Given two polynomial numbers represented by a linked list. Write a function that add these lists means add the coefficients who have same variable powers.
Example:

```Input:
1st number = 5x2 + 4x1 + 2x0
2nd number = -5x1 - 5x0
Output:
5x2-1x1-3x0
Input:
1st number = 5x3 + 4x2 + 2x0
2nd number = 5x^1 - 5x^0
Output:
5x3 + 4x2 + 5x1 - 3x0``` ## CPP

 `// C++ program for addition of two  ` `// polynomials using Linked Lists ` `#include ` `using` `namespace` `std; ` ` `  `// Node structure containing power  ` `// and coefficient of variable ` `struct` `Node  ` `{ ` `    ``int` `coeff; ` `    ``int` `pow``; ` `    ``struct` `Node* next; ` `}; ` ` `  `// Function to create new node ` `void` `create_node(``int` `x, ``int` `y,  ` `                 ``struct` `Node** temp) ` `{ ` `    ``struct` `Node *r, *z; ` `    ``z = *temp; ` `    ``if` `(z == NULL)  ` `    ``{ ` `        ``r = (``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` `        ``r->coeff = x; ` `        ``r->``pow` `= y; ` `        ``*temp = r; ` `        ``r->next = (``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` `        ``r = r->next; ` `        ``r->next = NULL; ` `    ``} ` `    ``else`  `    ``{ ` `        ``r->coeff = x; ` `        ``r->``pow` `= y; ` `        ``r->next = (``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` `        ``r = r->next; ` `        ``r->next = NULL; ` `    ``} ` `} ` ` `  `// Function Adding two polynomial  ` `// numbers ` `void` `polyadd(``struct` `Node* poly1,  ` `             ``struct` `Node* poly2, ` `             ``struct` `Node* poly) ` `{ ` `    ``while` `(poly1->next &&  ` `           ``poly2->next)  ` `    ``{ ` `        ``// If power of 1st polynomial is greater  ` `        ``// than 2nd, then store 1st as it is and  ` `        ``// move its pointer ` `        ``if` `(poly1->``pow` `> poly2->``pow``)  ` `        ``{ ` `            ``poly->``pow` `= poly1->``pow``; ` `            ``poly->coeff = poly1->coeff; ` `            ``poly1 = poly1->next; ` `        ``} ` ` `  `        ``// If power of 2nd polynomial is greater  ` `        ``// than 1st, then store 2nd as it is and  ` `        ``// move its pointer ` `        ``else` `if` `(poly1->``pow` `< poly2->``pow``)  ` `        ``{ ` `            ``poly->``pow` `= poly2->``pow``; ` `            ``poly->coeff = poly2->coeff; ` `            ``poly2 = poly2->next; ` `        ``} ` ` `  `        ``// If power of both polynomial numbers  ` `        ``// is same then add their coefficients ` `        ``else`  `        ``{ ` `            ``poly->``pow` `= poly1->``pow``; ` `            ``poly->coeff = (poly1->coeff +  ` `                           ``poly2->coeff); ` `            ``poly1 = poly1->next; ` `            ``poly2 = poly2->next; ` `        ``} ` ` `  `        ``// Dynamically create new node ` `        ``poly->next =  ` `              ``(``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` `        ``poly = poly->next; ` `        ``poly->next = NULL; ` `    ``} ` `    ``while` `(poly1->next || poly2->next)  ` `    ``{ ` `        ``if` `(poly1->next)  ` `        ``{ ` `            ``poly->``pow` `= poly1->``pow``; ` `            ``poly->coeff = poly1->coeff; ` `            ``poly1 = poly1->next; ` `        ``} ` `        ``if` `(poly2->next)  ` `        ``{ ` `            ``poly->``pow` `= poly2->``pow``; ` `            ``poly->coeff = poly2->coeff; ` `            ``poly2 = poly2->next; ` `        ``} ` `        ``poly->next =  ` `              ``(``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` `        ``poly = poly->next; ` `        ``poly->next = NULL; ` `    ``} ` `} ` ` `  `// Display Linked list ` `void` `show(``struct` `Node* node) ` `{ ` `    ``while` `(node->next != NULL)  ` `    ``{ ` `        ``printf``(``"%dx^%d"``, node->coeff,  ` `                ``node->``pow``); ` `        ``node = node->next; ` `        ``if` `(node->coeff >= 0)  ` `        ``{ ` `            ``if` `(node->next != NULL) ` `                ``printf``(``"+"``); ` `        ``} ` `    ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``struct` `Node *poly1 = NULL,  ` `                ``*poly2 = NULL,  ` `                ``*poly = NULL; ` ` `  `    ``// Create first list of 5x^2 +  ` `    ``// 4x^1 + 2x^0 ` `    ``create_node(5, 2, &poly1); ` `    ``create_node(4, 1, &poly1); ` `    ``create_node(2, 0, &poly1); ` ` `  `    ``// Create second list of -5x^1 -  ` `    ``// 5x^0 ` `    ``create_node(-5, 1, &poly2); ` `    ``create_node(-5, 0, &poly2); ` ` `  `    ``printf``(``"1st Number: "``); ` `    ``show(poly1); ` ` `  `    ``printf``(``"2nd Number: "``); ` `    ``show(poly2); ` ` `  `    ``poly = (``struct` `Node*)``malloc``(``sizeof``(``struct` `Node)); ` ` `  `    ``// Function add two polynomial  ` `    ``// numbers ` `    ``polyadd(poly1, poly2, poly); ` ` `  `    ``// Display resultant List ` `    ``printf``(``"Added polynomial: "``); ` `    ``show(poly); ` ` `  `    ``return` `0; ` `}`

Output:

```1st Number: 5x^2+4x^1+2x^0
2nd Number: -5x^1-5x^0

Time Complexity: O(m + n) where m and n are number of nodes in first and second lists respectively.

Recursive Method :

Algorithm:

1. If both the numbers are null then return
2. else if compare the power, if same then add the coefficients and recursively call addPolynomials on the next elements of both the numbers.
3. else if the power of the first number is greater then print the current element of the first number and recursively call addPolynomial on the next element of the first number and current element of the second number.
4. else print the current element of the second number and recursively call addPolynomial on the current element of first number and next element of second number.

## C++

 `//Program to add two polynomials represented in linkedlist using recursion ` `#include ` `using` `namespace` `std; ` `class` `Node{ ` `public``: ` `  ``int` `coeff,power; ` `  ``Node *next; ` `  ``Node(``int` `coeff, ``int` `power) ` `  ``{ ` `    ``this``->coeff = coeff; ` `    ``this``->power = power; ` `    ``this``->next = NULL; ` `  ``} ` `}; ` ` `  `void` `addPolynomials(Node *head1,  ` `                    ``Node *head2) ` `{ ` `  ``if``(head1==NULL &&  ` `     ``head2==NULL) ` `    ``return``; ` `  ``else` `if``(head1->power ==  ` `          ``head2->power) ` `  ``{ ` `    ``cout << ``" "` `<< head1->coeff +  head2->coeff <<  ` `            ``"x^"` `<< head1->power << ``" "``; ` `    ``addPolynomials(head1->next,head2->next); ` `  ``} ` `  ``else` `if``(head1->power > head2->power) ` `  ``{ ` `    ``cout << ``" "` `<< head1->coeff <<  ` `            ``"x^"` `<< head1->power << ``" "``; ` `    ``addPolynomials(head1->next, head2); ` `  ``} ` `  ``else` `  ``{ ` `    ``cout << ``" "` `<< head2->coeff <<  ` `            ``"x^"` `<< head2->power << ``" "``; ` `    ``addPolynomials(head1, head2->next); ` `  ``} ` `} ` ` `  `void` `insert(Node *head,  ` `            ``int` `coeff,  ` `            ``int` `power) ` `{ ` `  ``Node *new_node =  ` `        ``new` `Node(coeff,power); ` `  ``while``(head->next != NULL) ` `  ``{ ` `    ``head = head->next; ` `  ``} ` `  ``head->next = new_node; ` `} ` ` `  `void` `printList(Node *head) ` `{ ` `  ``cout << ``"Linked List"` `<< endl; ` `  ``while``(head != NULL) ` `  ``{ ` `    ``cout << ``" "` `<< head->coeff <<  ` `            ``"x"` `<< ``"^"` `<< head->power; ` `    ``head = head->next; ` `  ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `  ``Node *head=``new` `Node(5, 2); ` `  ``insert(head, 4, 1); ` `  ``Node *head2 = ``new` `Node(6, 2); ` `  ``insert(head2, 4, 1); ` `  ``printList(head); ` `  ``cout << endl; ` `  ``printList(head2); ` `  ``cout << endl <<  ` `          ``"Addition:"` `<< endl; ` `  ``addPolynomials(head,head2); ` ` `  ` `  `  ``return` `0; ` `} ` `//This code is contributed by Akshita Patel `

Output:

```Linked List
5x^2 4x^1
6x^2 4x^1