【leetcode】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.

将两个排好序的链表合并成一个链表。

一次5分钟写好的代码就ac了，正好刚下班，很开心

 //21. Merge Two Sorted Lists
	 public ListNode mergeTwoLists(ListNode l1, ListNode l2) 
	 {
		 if (l1 == null || l2 == null)
			 return l1 == null ? l2 : l1;
		 ListNode head = null;
		 if(l1.val < l2.val)
		 {
			 head = l1;
			 l1 = l1.next;
		 }else
		 {
			 head = l2;
			 l2 = l2.next;
		 }
		 ListNode p = head;
		 while(l1 != null && l2 != null)
		 {
			 if( l1.val < l2.val)
			 {
				 p.next = l1;
				 p = p.next;
				 l1 = l1.next;
			 }else
			 {
				 p.next = l2;
				 p = p.next;
				 l2 = l2.next;
			 }
		 }
		 p.next = l1 == null ? l2 : l1;
		 return head;
	 }