【LeetCode】Insertion Sort List

//用到O（N）的额外空间
public class Solution {
public ListNode insertionSortList(ListNode head) {
if(head==null||head.next==null)
return head;
ListNode root = new ListNode(head.val);
ListNode cur = head.next;
while(cur!=null){
ListNode tempNode = root;
ListNode pre = root;
while(tempNode!=null){
if(cur.val>tempNode.val){
pre=tempNode;
tempNode=tempNode.next;
}else{
break;
}
}
if(tempNode==root){
ListNode newNode = new ListNode(cur.val);
newNode.next=root;
root=newNode;
cur=cur.next;
}else if(tempNode==null){
ListNode newNode = new ListNode(cur.val);
pre.next=newNode;
cur=cur.next;
}else{
ListNode newNode = new ListNode(cur.val);
pre.next=newNode;
newNode.next=tempNode;
cur=cur.next;
}

}

return root;

}
}

public class NSolution {
public ListNode insertionSortList(ListNode head) {
if(head==null||head.next==null)
return head;

ListNode cur = head.next;
head.next=null;
while(cur!=null){
ListNode tempNode = head;
ListNode pre = head;
while(tempNode!=null){
if(cur.val>tempNode.val){
pre=tempNode;
tempNode=tempNode.next;
}else{
break;
}
}
if(tempNode==head){
ListNode newNode = new ListNode(cur.val);
newNode.next=head;
head=newNode;
cur=cur.next;

}else if(tempNode==null){
ListNode newNode = new ListNode(cur.val);
pre.next=newNode;
cur=cur.next;
}else{
ListNode newNode = new ListNode(cur.val);
pre.next=newNode;
newNode.next=tempNode;
cur=cur.next;
}

}

return head;

}
}