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) {
        if(list1 == null){
            return list2;
        }
        if(list2 == null){
            return list1;
        }
        ListNode pre = new ListNode(0);
        ListNode next1 = null,next2 = null,preTempNose = null;
        pre.next = list1;
        preTempNose = pre;
        while (list1 != null && list2 != null){
            next2 = list2.next;
            next1 = list1.next;
            if(list2.val < list1.val){
                list2.next = preTempNose.next;
                preTempNose.next = list2;
                list2 = next2;
            }
            else if(list2.val >= list1.val && (list1.next == null || (list1.next != null && list2.val < list1.next.val))){
                list1.next = list2;
                list2.next = next1;
                list1 = list2;
                list2 = next2;
            }
            else{
                list1 = next1;
            }
        }

        return pre.next;
    }
}