148. Sort List

Method 1: Merge Sorting ideas:

(1) Design a function to find the middle node, (2) design a merging of two already ordered functions; (3) the main function;

One of the first function thought: is in 109 to convert into BST in the same way, but also the speed of the list to solve the ring list of the design of the same idea!

 Public classSolution {PrivateListNode Findmidnode (ListNode head) {ListNode slow=Head; ListNode Fast=Head;  while(Fast.next! =NULL&& Fast.next.next! =NULL) {Slow=Slow.next; Fast=Fast.next.next; }        returnslow; }    Privatelistnode Merge (ListNode head1, ListNode head2) {ListNode dummy=NewListNode (0); ListNode Index=dummy;  while(Head1! =NULL&& head2! =NULL)        {            if(Head1.val <head2.val) {Index.next=Head1; Head1=Head1.next; }             Else{Index.next=head2; Head2=Head2.next; } Index=Index.next; }        if(Head1! =NULL) Index.next =Head1; ElseIndex.next =head2; returnDummy.next; }     PublicListNode sortlist (ListNode head) {if(Head = =NULL|| Head.next = =NULL){            returnHead; } ListNode Mid=Findmidnode (head); ListNode Left=sortlist (Mid.next); Mid.next=NULL; ListNode Right=Sortlist (head); returnmerge (Left,right); }}

148. Sort List