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MergeList.java
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69 lines (67 loc) · 1.67 KB
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/*
public class ListNode {
int val;
ListNode next = null;
ListNode(int val) {
this.val = val;
}
}*/
//递归版本
/*public class Solution {
public ListNode Merge(ListNode list1,ListNode list2) {
if(list1==null) return list2;
if(list2==null) return list1;
if(list1.val<=list2.val)
{
list1.next=Merge(list1.next,list2);
return list1;
}
else
{
list2.next=Merge(list1,list2.next);
return list2;
}
}
}*/
//非递归版本
public class Solution {
public ListNode Merge(ListNode list1,ListNode list2) {
if(list1==null) return list2;
if(list2==null) return list1;
ListNode headreturn=null;
ListNode current=null;
while(list1!=null && list2!=null)
{
if(list1.val<=list2.val)
{
if(headreturn==null)
{
headreturn=current=list1;
}
else{
current.next=list1;
current=current.next;
}
list1=list1.next;
}
else
{
if(headreturn==null)
{
headreturn=current=list2;
}
else
{
current.next=list2;
current=current.next;
}
list2=list2.next;
}
}
if(list1==null)
current.next=list2;
else
current.next=list1;
return headreturn;
}
}