题解 | 合并两个排序的链表

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pHead1 ListNode类
     * @param pHead2 ListNode类
     * @return ListNode类
     */
    public ListNode Merge (ListNode pHead1, ListNode pHead2) {
        // write code here
        ListNode p1 = pHead1;
        ListNode p2 = pHead2;
        ListNode cur = null;
        ListNode head = null;
        ListNode temp = null;
        while (p1 != null || p2  != null) {
            temp = cur;//记录上个节点
            // 一次性获取完剩下的节点
            if (p1 == null || p2 == null) {
                if (p1 == null) {
                    cur = p2;
                } else if (p2 == null) {
                    cur = p1;
                }
                if (head == null){
                    head = cur;
                }else{
                    temp.next = cur;
                }
                return head;
            }

            // 比较后，获取一个当前节点
            if (p1.val > p2.val) {
                cur = p2;
                p2 = p2.next;
            } else {
                cur = p1;
                p1 = p1.next;
            }
            if (head == null){
                head = cur;
            }else{
                temp.next = cur;                
            }
                
        }
        return head;
    }
}