Node Swapping

#include <iostream>
using namespace std;

class Node {
public:
    int data;
    Node* next;
};

class LinkedList {
private:
    Node* head;

public:
    LinkedList() {
        head = NULL;
    }

    void insertEnd(int value) {
        Node* newNode = new Node();
        newNode->data = value;
        newNode->next = NULL;

        if (head == NULL) {
            head = newNode;
            return;
        }

        Node* temp = head;
        while (temp->next != NULL) {
            temp = temp->next;
        }
        temp->next = newNode;
    }

    // ★ SWAP NODES by changing LINKS (not data) ★
    void swapNodes(int x, int y) {
        if (x == y) return;

        // Find node x and its previous
        Node* prevX = NULL;
        Node* currX = head;
        while (currX != NULL && currX->data != x) {
            prevX = currX;
            currX = currX->next;
        }

        // Find node y and its previous
        Node* prevY = NULL;
        Node* currY = head;
        while (currY != NULL && currY->data != y) {
            prevY = currY;
            currY = currY->next;
        }

        // If either x or y not found
        if (currX == NULL || currY == NULL) {
            cout << "One or both values not found!" << endl;
            return;
        }

        // If x is not head, link prevX to currY
        if (prevX != NULL)
            prevX->next = currY;
        else
            head = currY;

        // If y is not head, link prevY to currX
        if (prevY != NULL)
            prevY->next = currX;
        else
            head = currX;

        // Swap next pointers
        Node* temp = currY->next;
        currY->next = currX->next;
        currX->next = temp;
    }

    void display() {
        Node* temp = head;
        while (temp != NULL) {
            cout << temp->data << " -> ";
            temp = temp->next;
        }
        cout << "NULL" << endl;
    }
};

int main() {
    LinkedList list;
    list.insertEnd(10);
    list.insertEnd(20);
    list.insertEnd(30);
    list.insertEnd(40);
    list.insertEnd(50);

    cout << "Before swap:" << endl;
    list.display();
    // 10 -> 20 -> 30 -> 40 -> 50 -> NULL

    list.swapNodes(20, 40);

    cout << "After swapping 20 and 40:" << endl;
    list.display();
    // 10 -> 40 -> 30 -> 20 -> 50 -> NULL

    return 0;
}