Check Palindrom in a Linked List and Add 2 numbers in Linked List

Author: alisamad1

Linked_List/Add_2_Numbers.cpp

@@ -0,0 +1,74 @@
+#include <iostream>
+using namespace std;
+struct Node {
+    int data;
+    Node* next;
+    Node(int val) : data(val), next(nullptr) {}
+};
+Node* reverse(Node* head) {
+    Node* prev = nullptr;
+    Node* current = head;
+    Node* next = nullptr;
+    while (current != nullptr) {
+        next = current->next;
+        current->next = prev;
+        prev = current;
+        current = next;
+    }
+    return prev;
+}
+void insertAtTail(Node*& head, Node*& tail, int val) {
+    Node* temp = new Node(val);
+    if (head == nullptr) {
+        head = temp;
+        tail = temp;
+    } else {
+        tail->next = temp;
+        tail = temp;
+    }
+}
+Node* addTwoNumbers(Node* first, Node* second) {
+    int carry = 0;
+    Node* ansHead = nullptr;
+    Node* ansTail = nullptr;
+    while (first != nullptr || second != nullptr || carry != 0) {
+        int val1 = (first != nullptr) ? first->data : 0;
+        int val2 = (second != nullptr) ? second->data : 0;
+        int sum = carry + val1 + val2;
+        int digit = sum % 10;
+        carry = sum / 10;
+        insertAtTail(ansHead, ansTail, digit);
+        if (first != nullptr) first = first->next;
+        if (second != nullptr) second = second->next;
+    }
+    return ansHead;
+}
+Node* addTwoLists(Node* first, Node* second) {
+    first = reverse(first);
+    second = reverse(second);
+    Node* ans = addTwoNumbers(first, second);
+    ans = reverse(ans);
+    return ans;
+}
+// Helper function to print list
+void printList(Node* head) {
+    while (head != nullptr) {
+        cout << head->data << " ";
+        head = head->next;
+    }
+    cout << endl;
+}
+// Example usage
+int main() {
+    Node* first = nullptr;
+    Node* tail1 = nullptr;
+    insertAtTail(first, tail1, 4);
+    insertAtTail(first, tail1, 5);  // Represents 45
+    Node* second = nullptr;
+    Node* tail2 = nullptr;
+    insertAtTail(second, tail2, 3);
+    insertAtTail(second, tail2, 4); // Represents 34
+    Node* result = addTwoLists(first, second);
+    printList(result); // Should print 7 9 for 79
+    return 0;
+}

Linked_List/Check_Palindrome_LL.cpp

@@ -0,0 +1,53 @@
+#include<iostream>
+#include<vector>
+using namespace std;
+struct Node{
+    int data;
+    Node * next;
+    Node(int val) : data(val), next(nullptr) {}
+};
+bool checkPalindrome(vector<int>& arr){
+    int n = arr.size();
+    int start = 0;
+    int end = n - 1;
+    while(start <= end){
+        if(arr[start] != arr[end]){
+            return false;
+        }
+        start++;
+        end--;
+    }
+    return true;
+}
+bool isPalindrome(Node * head){
+    vector<int> arr;
+    Node * temp = head;
+    while(temp != NULL){
+        arr.push_back(temp->data);
+        temp = temp->next;
+    }
+    return checkPalindrome(arr);
+}
+void printList(Node * head){
+    Node * current = head;
+    while(current != NULL){
+        cout << current->data ;
+        current = current->next;
+    }
+    cout << endl;
+}
+int main(){
+    Node * head = new Node(1);
+    head->next = new Node(2);
+    head->next->next = new Node(3);
+    head->next->next->next = new Node(3);
+    head->next->next->next->next = new Node(2);
+    head->next->next->next->next->next = new Node(1);
+    if(isPalindrome(head)){
+        cout << "The Given Linked List is a Palindrome. " << endl;
+    }
+    else{
+        cout << "The Given Linked List is not a Palindrome. " << endl;
+    }
+    return 0;
+}