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
		//排异
	     if(pHead1 == null){
		  return pHead2;
		 }
		 if(pHead2 == null){
		    return pHead1;
		 }
		 ListNode start = pHead1.val>pHead2.val?pHead2:pHead1;
		 ListNode dummy = new ListNode(0);
		 dummy.next = start;
		 ListNode h1 = pHead1.val>pHead2.val?pHead1:pHead1.next;
		 ListNode h2 = pHead1.val>pHead2.val?pHead2.next:pHead2;
		 while(h1!= null && h2 !=null){
		 if(h1.val > h2.val){
			start.next = h2;
			h2 = h2.next;
			start = start.next;
		 }else{
			start.next = h1;
			h1 = h1.next;
			start = start.next;
		 }
		 }
		 if(h1!=null){
			 start.next = h1;
		 }else{
		     start.next = h2;
		 }
		 return dummy.next;

    }
}