Merge Two Sorted Lists
描述
Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.
分析
无
代码
// Merge Two Sorted Lists
// 时间复杂度O(min(m,n))，空间复杂度O(1)
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
if (l1 == nullptr) return l2;
if (l2 == nullptr) return l1;
ListNode dummy(-1);
ListNode *p = &dummy;
for (; l1 != nullptr && l2 != nullptr; p = p->next) {
if (l1->val > l2->val) { p->next = l2; l2 = l2->next; }
else { p->next = l1; l1 = l1->next; }
}
p->next = l1 != nullptr ? l1 : l2;
return dummy.next;
}
};