[LeetCode]Insertion Sort List

题目描述：

Sort a linked list using insertion sort.

解决方案:

该题目就是用插入排序来对链表进行排序，很简单，直接上代码。

class Solution {
public:
    ListNode *insertionSortList(ListNode *head) {
        ListNode *q = head;
        ListNode *temp = new ListNode(0);
        temp->val = INT_MIN;
        temp->next = NULL;
        ListNode *p = temp;
        ListNode * pre = NULL;
        ListNode *k = NULL;
        ListNode *f = NULL;
        while (q != NULL) {
            f = q;
            q = q->next;
            k = temp;
            while(1) {
                if (k == NULL) {
                    f->next = NULL;
                    pre->next = f;
                    break;
                }
                if (f->val < k->val) {
                    f->next = pre->next;
                    pre->next = f;
                    pre = k;
                    break;
                }
                pre = k;
                k = k->next;
            }
            pre = NULL; 
        }
        p = temp->next;
        temp->next = NULL;
        delete temp;
        return p;
    }
};