Sort a linked list using insertion sort.
还是插入排序简单呀。
/**
* 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 || head->next == NULL) {
return head;
}
ListNode *cur = head->next;
head->next = NULL;
ListNode *prev = NULL;
ListNode *target = NULL;
ListNode *tmp = NULL;
while (cur != NULL) {
prev = NULL;
target = head;
while (target != NULL && target->val <= cur->val) {
prev = target;
target = target->next;
}
if (prev == NULL) {
head = cur;
}
else {
prev->next = cur;
}
tmp = cur->next;
cur->next = target;
cur = tmp;
}
return head;
}
};