mergeTwoSortedLists.cpp

// Merge Two Sorted Lists

#include <iostream>

struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};

ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
    ListNode* dummy = new ListNode(0);
    ListNode* current = dummy;
    
    while (l1 && l2) {
        if (l1->val < l2->val) {
            current->next = l1;
            l1 = l1->next;
        } else {
            current->next = l2;
            l2 = l2->next;
        }
        current = current->next;
    }
    
    if (l1) {
        current->next = l1;
    } else {
        current->next = l2;
    }
    
    return dummy->next;
}

// Example usage
int main() {
    ListNode* l1 = new ListNode(1);
    l1->next = new ListNode(3);
    l1->next->next = new ListNode(5);

    ListNode* l2 = new ListNode(2);
    l2->next = new ListNode(4);
    l2->next->next = new ListNode(6);

    ListNode* mergedList = mergeTwoLists(l1, l2);

    while (mergedList != NULL) {
        std::cout << mergedList->val << " ";
        mergedList = mergedList->next;
    }

    return 0;
}