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feat:Add Polynomial Addition (#600)
* feat:Add Polynomial Addition * Review changes * updating DIRECTORY.md * Apply suggestions from code review Co-authored-by: David Leal <[email protected]> * Corrected printing Co-authored-by: David Leal <[email protected]> * file path fixed * updating DIRECTORY.md * Corrected free memory Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> Co-authored-by: David Leal <[email protected]>
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‎DIRECTORY.md

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* [Mirror](https://github.com/TheAlgorithms/C/blob/master/misc/mirror.c)
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* [Palindrome](https://github.com/TheAlgorithms/C/blob/master/misc/palindrome.c)
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* [Pid](https://github.com/TheAlgorithms/C/blob/master/misc/pid.c)
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* [Poly Add](https://github.com/TheAlgorithms/C/blob/master/misc/poly_add.c)
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* [Prime](https://github.com/TheAlgorithms/C/blob/master/misc/prime.c)
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* [Prime Factoriziation](https://github.com/TheAlgorithms/C/blob/master/misc/prime_factoriziation.c)
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* [Quartile](https://github.com/TheAlgorithms/C/blob/master/misc/quartile.c)

‎misc/poly_add.c

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/**
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* @file
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* @brief Implementation of [Addition of two polynomials]
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* (https://en.wikipedia.org/wiki/Polynomial#Addition)
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* @author [Ankita Roy Chowdhury](https://github.com/Ankita19ms0010)
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* @details
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* This code takes two polynomials as input
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* and prints their sum using linked list.
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* The polynomials must be in increasing or decreasing order of degree.
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* Degree must be positive.
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*/
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#include <stdio.h> // for io operations
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#include <stdlib.h>
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/**
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* @brief identifier for single-variable polynomial coefficients as a linked
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* list
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*/
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struct term
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{
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int coef; /**< coefficient value */
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int pow; /**< power of the polynomial term */
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struct term *next; /**< pointer to the successive term */
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};
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/**
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* @brief Frees memory space
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* @param poly first term of polynomial
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* @returns void
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*/
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void free_poly(struct term *poly)
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{
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if (!poly)
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{
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return; // NULL pointer does not need delete
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}
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else
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{
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while (!poly->next)
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{
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free(poly->next); // Deletes next term
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}
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free(poly); // delete the current term
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}
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}
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/**
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* The function will create a polynomial
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* @param poly stores the address of the polynomial being created
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* @param coef contains the coefficient of the node
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* @param pow contains the degree
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* @returns none
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*/
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void create_polynomial(struct term **poly, int coef, int pow)
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{
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// Creating the polynomial using temporary linked lists
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struct term *temp1, *temp2;
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temp1 = *poly; // Contains the null pointer
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// Initiating first term
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if (temp1 == NULL)
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{
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temp2 = (struct term *)malloc(
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sizeof(struct term)); // Dynamic node creation
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temp2->coef = coef;
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temp2->pow = pow;
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// Updating the null pointer with the address of the first node of the
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// polynomial just created
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*poly = temp2;
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temp2->next = NULL; // Increasing the pointer temp2
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}
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// Creating the rest of the nodes
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else
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{
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temp2->next = (struct term *)malloc(
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sizeof(struct term)); // Dynamic node creation
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temp2 = temp2->next; // Increasing the pointer temp2
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temp2->coef = coef;
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temp2->pow = pow;
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temp2->next = NULL;
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}
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}
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/**
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* The function will add 2 polynomials
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* @param poly1 first polynomial of the addition
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* @param poly2 second polynomial of the addition
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* @param pol the resultant polynomial
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*/
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void poly_add(struct term **pol, struct term *poly1, struct term *poly2)
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{
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// Creating a temporary linked list to store the resultant polynomial
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struct term *temp = (struct term *)malloc(sizeof(struct term));
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temp->next = NULL;
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*pol =
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temp; //*pol always points to the 1st node of the resultant polynomial
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// Comparing the powers of the nodes of both the polynomials
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// until one gets exhausted
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while (poly1 && poly2)
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{
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/* If the power of the first polynomial is greater than the power of the
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second one place the power and coefficient of that node of the first
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polynomial in temp and increase the pointer poly1
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*/
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if (poly1->pow > poly2->pow)
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{
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temp->coef = poly1->coef;
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temp->pow = poly1->pow;
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poly1 = poly1->next;
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}
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/* If the power of the second polynomial is greater than the power of
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the first one place the power and coefficient of that node of the
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second polynomial in temp and increase the pointer poly2
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*/
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else if (poly1->pow < poly2->pow)
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{
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temp->coef = poly2->coef;
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temp->pow = poly2->pow;
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poly2 = poly2->next;
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}
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/* If both of them have same power then sum the coefficients
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place both the summed coefficient and the power in temp
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increase both the pointers poly1 and poly2
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*/
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else
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{
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temp->coef = poly1->coef + poly2->coef;
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temp->pow = poly1->pow;
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poly1 = poly1->next;
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poly2 = poly2->next;
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}
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/* If none of the polynomials are exhausted
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dynamically create a node in temp
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*/
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if (poly1 && poly2)
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{
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temp->next = (struct term *)malloc(
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sizeof(struct term)); // Dynamic node creation
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temp = temp->next; // Increase the pointer temp
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temp->next = NULL;
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}
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}
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/* If one of the polynomials is exhausted
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place the rest of the other polynomial as it is in temp
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by creating nodes dynamically
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*/
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while (poly1 || poly2)
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{
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temp->next = (struct term *)malloc(
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sizeof(struct term)); // Dynamic node creation
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temp = temp->next; // Increasing the pointer
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temp->next = NULL;
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/* If poly1 is not exhausted
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place rest of that polynomial in temp
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*/
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if (poly1)
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{
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temp->coef = poly1->coef;
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temp->pow = poly1->pow;
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poly1 = poly1->next;
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}
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/* If poly2 is not exhausted
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place rest of that polynomial in temp
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*/
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else if (poly2)
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{
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temp->coef = poly2->coef;
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temp->pow = poly2->pow;
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poly2 = poly2->next;
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}
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}
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}
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/**
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* The function will display the polynomial
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* @param poly first term of the polynomial to be displayed
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* @returns none
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*/
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void display_polynomial(struct term *poly)
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{
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while (poly != NULL)
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{
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printf("%d x^%d", poly->coef, poly->pow);
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poly = poly->next;
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if (poly != NULL)
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{
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printf(" + ");
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}
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}
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}
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/**
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* @brief Test function 1
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*
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* @details
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* Polynomial 1 is 5 x^2 + 3 x^1 + 2 x^0
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* Polynomial 2 is 7 x^3 + 9 x^1 + 10 x^0
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* Resultant polynomial is 7 x^3 + 5 x^2 + 12 x^1 + 12 x^0
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* @returns void
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*/
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static void test1(struct term *poly1, struct term *poly2, struct term *poly3)
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{
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printf("\n----Test 1----\n");
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printf("\nFirst Polynomial:\n"); // Defining the 1st polynomial
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create_polynomial(&poly1, 5, 2);
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create_polynomial(&poly1, 3, 1);
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create_polynomial(&poly1, 2, 0);
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display_polynomial(poly1);
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printf("\nSecond Polynomial:\n"); // Defining the 2nd polynomial
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create_polynomial(&poly2, 7, 3);
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create_polynomial(&poly2, 9, 1);
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create_polynomial(&poly2, 10, 0);
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display_polynomial(poly2);
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poly_add(&poly3, poly1, poly2); // Adding the two polynomials
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printf("\nResultant polynomial:\n");
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display_polynomial(poly3);
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printf("\n");
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// Frees memory space
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free_poly(poly1);
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free_poly(poly2);
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free_poly(poly3);
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}
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/**
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* @brief Test function 2
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*
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* @details
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* Polynomial 1 is 3 x^5 + 1 x^4 + 2 x^3 + -2 x^1 + 5 x^0
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* Polynomial 2 is 2 x^5 + 3 x^3 + 7 x^1 + 2 x^0
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* Resultant polynomial is 5 x^5 + 1 x^4 + 5 x^3 + 5 x^1 + 7 x^0
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* @returns void
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*/
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static void test2(struct term *poly1, struct term *poly2, struct term *poly3)
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{
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printf("\n----Test 2----\n");
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printf("\nFirst Polynomial:\n"); // Defining the 1st polynomial
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create_polynomial(&poly1, 3, 5);
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create_polynomial(&poly1, 1, 4);
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create_polynomial(&poly1, 2, 3);
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create_polynomial(&poly1, -2, 1);
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create_polynomial(&poly1, 5, 0);
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display_polynomial(poly1);
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printf("\nSecond Polynomial:\n"); // Defining the 2nd polynomial
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create_polynomial(&poly2, 2, 5);
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create_polynomial(&poly2, 3, 3);
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create_polynomial(&poly2, 7, 1);
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create_polynomial(&poly2, 2, 0);
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display_polynomial(poly2);
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poly_add(&poly3, poly1, poly2); // Adding the two polynomials
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printf("\nResultant polynomial:\n");
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display_polynomial(poly3);
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printf("\n");
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// Frees memory space
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free_poly(poly1);
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free_poly(poly2);
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free_poly(poly3);
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}
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/**
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* @brief Test function 3
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*
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* @details
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* Polynomial 1 is -12 x^0 + 8 x^1 + 4 x^3
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* Polynomial 2 is 5 x^0 + -13 x^1 + 3 x^3
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* Resultant polynomial is -7 x^0 + -5 x^1 + 7 x^3
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* @returns void
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*/
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static void test3(struct term *poly1, struct term *poly2, struct term *poly3)
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{
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printf("\n----Test 3----\n");
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printf("\nFirst Polynomial:\n"); // Defining the 1st polynomial
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create_polynomial(&poly1, -12, 0);
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create_polynomial(&poly1, 8, 1);
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create_polynomial(&poly1, 4, 3);
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display_polynomial(poly1);
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printf("\nSecond Polynomial:\n"); // Defining the 2nd polynomial
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create_polynomial(&poly2, 5, 0);
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create_polynomial(&poly2, -13, 1);
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create_polynomial(&poly2, 3, 3);
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display_polynomial(poly2);
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poly_add(&poly3, poly1, poly2); // Adding the two polynomials
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printf("\nResultant polynomial:\n");
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display_polynomial(poly3);
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printf("\n");
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// Frees memory space
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free_poly(poly1);
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free_poly(poly2);
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free_poly(poly3);
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}
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/**
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* @brief Main function
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* @returns 0 on exit
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*/
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int main(void)
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{
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struct term *poly1 = NULL, *poly2 = NULL, *poly3 = NULL;
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test1(poly1, poly2, poly3);
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test2(poly1, poly2, poly3);
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test3(poly1, poly2, poly3);
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return 0;
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}

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