题解 | #合并两个排序的链表#

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
        ListNode we =list1;
        ListNode you= list1;
        if(list1 == null && list2 == null){
            return null;
        }
        if(list1 == null){
            return  list2;
        }
        if(list2 == null){
            return list1;
        }
         if(list1.val <= list2.val){
                we=list1;
                list1=list1.next;
         }
        else{
            we = list2;
            list2 = list2.next;
        }
        you = we;
        int listone=0;
        while(true){
            if(list1 == null){
                listone = 1;
                break;
            }
            if(list2 == null){
                break;
            }
            if(list1.val <= list2.val){
                we.next = list1;
                list1 = list1.next;
                we = we.next;
            }
            else{
                we.next = list2;
                list2 = list2.next;
                we = we.next;
            }
            
        }
        if(listone == 1){
            we.next = list2;
            return you;
        }
        else{
            we.next = list1;
            return you;
        }
    }
}