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
        /**
         思路分析：
         1.循环合并
         */
        if(pHead1 == null){
            return pHead2;
        }
        if(pHead2 == null){
            return pHead1;
        }
        ListNode p = pHead1;
        ListNode q = pHead2;
        ListNode newHead = new ListNode(-1);
        ListNode cur = newHead;

        while (p != null && q != null) {
            if (p.val < q.val) {//要么p后移要么q后移
                cur.next = p;
                p = p.next;
            } else {
                cur.next = q;
                q = q.next;
            }
            cur = cur.next;
        }
        if(p == null){
            cur.next = q;
        }
        if(q == null){
            cur.next = p;
        }
        return newHead.next;
    }
}