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 tmp;
        ListNode tmpsmall;
        ListNode pStart;
        ListNode pOther;
        ListNode headnext;

        int oth, sn;

        if (pHead1 != null && pHead2==null) {
            pStart = pHead1;
            pOther = pHead2;
        }

        else if (pHead1 != null && pHead1.val <= pHead2.val) {
            pStart = pHead1;
            pOther = pHead2;
        } 
        else {
            pStart = pHead2;
            pOther = pHead1;
        }

        if (pStart == null) return null;

        ListNode res = pStart;
        while (true) {
            if (pStart.next == null && pOther == null) break;



            if (pOther == null) {
                tmp = pOther;
                tmpsmall = pStart.next;
            }
            else if(pStart.next == null){
                tmp = pStart.next; //记录较大节点
                tmpsmall = pOther;
            }
            else if (pOther.val <= pStart.next.val) {
                tmp = pStart.next; //记录较大节点
                tmpsmall = pOther;
            } 
            else {
                tmp = pOther;
                tmpsmall = pStart.next;
            }

            pStart.next = tmpsmall;
            pStart = pStart.next;
            pOther = tmp;

        }

        return res;
    }
}