Polynomial Multiplication Using Linked Lists

docs/linked-list/Polynomial_multiplication.cpp

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+//Write a C++ program to multiply two polynomials using singly linked lists. Each polynomial should be represented as a linked list where each node contains a coefficient and an exponent for a term.
+//The program should take user input for two polynomials, perform the multiplication, and display the result.
+
+//APPROACH-
+/*The provided C++ code implements polynomial multiplication using a linked list.
+1) Node Structure: Each term of the polynomial is represented by a Node containing the coefficient, exponent, and a pointer to the next term.
+2) Adding Terms: The addTerm function adds new terms to the polynomial. It appends terms to the end of the linked list.
+3) Displaying Polynomials: The display function formats and prints the polynomial, handling the sign between terms.
+4) Multiplying Polynomials: The multiplyPolynomials function multiplies two polynomials by iterating through each term of both polynomials, combining like terms as needed.
+5) Main Function: It handles user input for the polynomials, displays them, performs the multiplication, and shows the result.*/
+
+#include <iostream>
+using namespace std;
+
+// Node structure for polynomial terms
+struct Node {
+    int coeff; // Coefficient of the term
+    int exp;   // Exponent of the term
+    Node* next; // Pointer to the next term
+    Node(int c, int e) : coeff(c), exp(e), next(nullptr) {}
+};
+
+// Function to add a new term to the polynomial
+void addTerm(Node*& poly, int coeff, int exp) {
+    Node* newNode = new Node(coeff, exp);
+    if (!poly) {
+        poly = newNode;
+    } else {
+        Node* temp = poly;
+        while (temp->next)
+            temp = temp->next;
+        temp->next = newNode;
+    }
+}
+
+// Function to display the polynomial
+void display(Node* poly) {
+    if (!poly) {
+        cout << "0" << endl;
+        return;
+    }
+    bool firstTerm = true;
+    while (poly) {
+        if (firstTerm) {
+            firstTerm = false;
+        } else if (poly->coeff > 0) {
+            cout << " + ";
+        }
+        cout << poly->coeff << "x^" << poly->exp;
+        poly = poly->next;
+    }
+    cout << endl;
+}
+
+// Function to multiply two polynomials and return the resulting polynomial
+Node* multiplyPolynomials(Node* poly1, Node* poly2) {
+    if (!poly1 || !poly2) return nullptr;
+
+    Node* result = nullptr;
+
+    // Traverse each term of the first polynomial
+    for (Node* p1 = poly1; p1; p1 = p1->next) {
+        // Traverse each term of the second polynomial
+        for (Node* p2 = poly2; p2; p2 = p2->next) {
+            int coeff = p1->coeff * p2->coeff;
+            int exp = p1->exp + p2->exp;
+            // Insert term in result, combining like terms
+            Node* temp = result;
+            Node* prev = nullptr;
+            bool combined = false;
+            while (temp) {
+                if (temp->exp == exp) { // Combine like terms
+                    temp->coeff += coeff;
+                    combined = true;
+                    break;
+                }
+                if (temp->exp < exp) break;
+                prev = temp;
+                temp = temp->next;
+            }
+            if (!combined) {
+                Node* newNode = new Node(coeff, exp);
+                if (!prev) { // Insert at the beginning
+                    newNode->next = result;
+                    result = newNode;
+                } else { // Insert in between or end
+                    newNode->next = prev->next;
+                    prev->next = newNode;
+                }
+            }
+        }
+    }
+
+    return result;
+}
+
+// Main function
+int main() {
+    Node* poly1 = nullptr;
+    Node* poly2 = nullptr;
+
+    // Input first polynomial
+    int terms;
+    cout << "Enter number of terms for the first polynomial: ";
+    cin >> terms;
+    cout << "Enter coefficient and exponent for each term:" << endl;
+    for (int i = 0; i < terms; ++i) {
+        int coeff, exp;
+        cin >> coeff >> exp;
+        addTerm(poly1, coeff, exp);
+    }
+
+    // Input second polynomial
+    cout << "Enter number of terms for the second polynomial: ";
+    cin >> terms;
+    cout << "Enter coefficient and exponent for each term:" << endl;
+    for (int i = 0; i < terms; ++i) {
+        int coeff, exp;
+        cin >> coeff >> exp;
+        addTerm(poly2, coeff, exp);
+    }
+
+    // Display both polynomials
+    cout << "First polynomial: ";
+    display(poly1);
+    cout << "Second polynomial: ";
+    display(poly2);
+
+    // Multiply the polynomials
+    Node* result = multiplyPolynomials(poly1, poly2);
+
+    // Display result
+    cout << "Result of multiplication: ";
+    if (result) {
+        display(result);
+    } else {
+        cout << "Both polynomials are empty." << endl;
+    }
+
+    return 0;
+}