Insertion Sort List

Sort a linked list using insertion sort.

/**

 * Definition for singly-linked list.

 * struct ListNode {

 *     int val;

 *     ListNode *next;

 *     ListNode(int x) : val(x), next(NULL) {}

 * };

 */

class Solution {

public:

    ListNode *insertionSortList(ListNode *head) 

    {

        if(head==NULL) return NULL;

        ListNode* phead=new ListNode(getmin(head));

        ListNode* p1=phead;

        while(head!=NULL)

        {

            ListNode* p2=new ListNode(getmin(head));

            p1->next=p2;

            p1=p2;

        }

        return phead;

    }

    int getmin(ListNode* &head)

    {

        if(head->next==NULL)

        {

            int val=head->val;

            head=NULL;

            return val;

        }

        ListNode* pre=NULL;

        int val=head->val;

        

        ListNode* p2=head;

        while(p2->next!=NULL)

        {

            if(p2->next->val<val) 

            {

                val=p2->next->val;

                pre=p2;            

            }

            p2=p2->next;

        }

        if(pre==NULL)

        {

            head=head->next;

        }

        else

            pre->next=pre->next->next;

        return val;

    }

};