자바 구현 - 두 개의 질서 있 는 링크 통합

package com.bittech;

/**
 * Author:weiwei
 * description:        
 * Creat:2019/5/6
 **/
public class MergeList {

    public class ListNode{
        int val;
        ListNode next;

        ListNode(int x){
            val = x;
        }
    }
    private static ListNode Merge(ListNode listA,ListNode listB){
        if(listA == null){
            return listB;
        }
        if(listB == null){
            return listA;
        }

        /**
         *            ,         
         *              ,      ,           
         *         
         *               ,                    
         */

        ListNode result = null;  //                  ,   null
        ListNode last = null;    //             
        ListNode nA = listA;
        ListNode nB = listB;
        //           
        while(nA != null && nB != null){
            if(nA.val <= nB.val){
                if(result == null){
                    result = nA;
                }else{
                    last.next = nA;
                }
                //last    
                last = nA;
                nA = nA.next;
            }else{
                if(result == null){
                    result = nB;
                }else{
                    last.next = nB;
                }
                //last    
                last = nB;
                nB = nB.next;
            }
        }
        //            
        if(nA != null){
            //nA           
            last.next = nA;
        }else{
            //nB          
            last.next = nB;
        }
        return result;
    }
}