leetcode----------Merge Two Sorted Lists

題目	Merge Two Sorted Lists
經過率	33.2%
難度	Easy

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.

 

 關鍵點：定義一個新的指針，而後取出兩個鏈表中各自的第一個元素進行比較，將較小者加入新鏈表。最後當其中一個鏈表變爲空後，將另外一個鏈表剩餘全部元素加入新鏈表。

   java代碼：

    

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode p1=l1;
        ListNode p2=l2;
        ListNode mergedList = new ListNode(0);
        ListNode p=mergedList;
        while(p1!=null&&p2!=null){
            if(p1.val<=p2.val){
                p.next=p1;
                p1=p1.next;
            }else{
                p.next=p2;
                p2=p2.next;
            }
            p=p.next;
        }
        if(p1!=null){
            p.next=p1;
        }
        if(p2!=null){
            p.next=p2;
        }
        return mergedList.next;
    }
}