[leetcode]Insertion Sort List

如果那天前先做了这道题就好了。。言归正传，需要两个dummy节点，本质上就是从原来的链表中删除最小的，加到新的链表中去。

class Solution {

public:

    ListNode *insertionSortList(ListNode *head) {

        ListNode *o_dummy = new ListNode(0);

        ListNode *n_dummy = new ListNode(0);

        o_dummy->next = head;

        ListNode *last = n_dummy;

        while (o_dummy->next != NULL) {

            ListNode *prev = o_dummy;

            ListNode *node = prev->next;

            // find node with min val

            ListNode *min_node = node;

            ListNode *prev_node = prev;

            while (node != NULL) {

                if (node->val < min_node->val) {

                    min_node = node;

                    prev_node = prev;

                }

                node = node->next;

                prev = prev->next;

            }

            prev_node->next = min_node->next;

            

            // insert to new list

            min_node->next = NULL;

            last->next = min_node;

            last = min_node;

        }

        return n_dummy->next;

    }

};