Insertion Sort List

Sort a linked list using insertion sort.

/**
* 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;

vector<int> vec;
ListNode *p = head;
while(p != NULL)
{
vec.push_back(p->val);
p = p->next;
}

for(int i = 1; i < vec.size(); i++)
{
int tmp = vec[i];
int j;
for(j = i; j > 0 && tmp < vec[j-1]; j--)
vec[j] = vec[j-1];

vec[j] = tmp;
}

p = head;
for(vector<int>::iterator it = vec.begin(); it != vec.end(); it++, p = p->next)
p->val = *it;

return head;
}
};