21. Merge Two Sorted Lists

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.

排序链表归并

package leet//Definition for singly-linked list.type ListNode struct {    Val  int    Next *ListNode}func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {    head := ListNode{0, nil}    next := &head    head1, head2 := l1, l2    for head1 != nil && head2 != nil {        if head1.Val > head2.Val {            next.Next = head2            head2 = head2.Next        } else {            next.Next = head1            head1 = head1.Next        }        next = next.Next    }    if head1 != nil {        next.Next = head1    }    if head2 != nil {        next.Next = head2    }    return head.Next}