Insertion Sort List

Insertion Sort List

 

Sort a linked list using insertion sort.

ListNode *insertionSortList(ListNode *head) {//添加一个最小头结点，然后添加一个定位置的函数
       ListNode  dummy(INT_MIN);
       for(ListNode* cur =head;cur !=nullptr;)
       {
           auto pos =findInsertPos(&dummy,cur->val);
           ListNode* tmp =cur->next;
           cur->next =pos->next;
           pos->next =cur;
           cur =tmp;
       }
       return dummy.next;
    }
    
    ListNode* findInsertPos(ListNode* head,int x)
    {
        ListNode* pre=nullptr;
        for(ListNode* cur =head;cur!=nullptr&&cur->val <=x;pre =cur,cur =cur->next)
            ;
        return pre;
    }