# Merge Two Sorted Lists Problem & Solution

Merge two sorted linked lists and return it as a sorted list. The list should be made by splicing together the nodes of the first two lists.

## C++ Solution

#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

/**
* struct ListNode {
*   int val;
*   ListNode *next;
*   ListNode() : val(0), next(nullptr) {}
*   ListNode(int x) : val(x), next(nullptr) {}
*   ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
if (l1 == nullptr) {
return l2;
}

if (l2 == nullptr) {
return l1;
}

ListNode* root = new ListNode();
ListNode* cursor = root;

while (l1 != nullptr && l2 != nullptr) {
if (l1->val > l2->val) {
cursor->next = l2;
l2 = l2->next;
cursor = cursor->next;
} else {
cursor->next = l1;
l1 = l1->next;
cursor = cursor->next;
}
}

if (l1 != nullptr) {
cursor->next = l1;
}

if (l2 != nullptr) {
cursor->next = l2;
}

cursor = root->next;
delete root;

return cursor;
}
};