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

Java

// Merge Two Sorted Lists
// 时间复杂度O(min(m,n))，空间复杂度O(1)
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null) return l2;
        if (l2 == null) return l1;
        ListNode dummy = new ListNode(-1);
        ListNode p = dummy;
        for (; l1 != null && l2 != null; p = p.next) {
            if (l1.val > l2.val) { p.next = l2; l2 = l2.next; }
            else { p.next = l1; l1 = l1.next; }
        }
        p.next = l1 != null ? l1 : l2;
        return dummy.next;
    }
}

C++

// 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;
    }
};

相关题目

• Merge Two Sorted Arrays
• Merge k Sorted Lists