[LeetCode]Insertion Sort List

class Solution {
public:
ListNode* insertionSortList(ListNode* head) {
if(head == nullptr) return nullptr;
ListNode * pre = new ListNode(0);
pre->next = head; //链条的内容随时在改变，写代码时特别注意
int k = 0;
while(true){
ListNode *nex = pre;
int temp = k;
while(temp>0){
nex = nex ->next; //每次遍历，找到最后一个点，注意链表排序后各个点的位置改变了
--temp;
}
k++;
if(nex->next==nullptr) break;
else insertList(pre,nex);
}
return pre->next;
}
void insertList(ListNode* pre,ListNode *front){//在链条中插入最后的一个点
ListNode* head = pre->next;
ListNode* last = front->next;
if(head==last)
return ;
while(head!=last){
if(head->val>last->val){
pre->next = last;
front->next = last->next;
last->next = head;
break; //找到插入点终止循环
}
pre = pre->next;
head = head->next;
}
}
};