Leetcode习题：Insertion Sort List

Insertion Sort List

public class Solution {
public ListNode insertionSortList(ListNode head) {
if (head == null) {
return null;
}

ListNode p1 = head.next;
head.next = null;

while (p1 != null) {
ListNode prev = null;
ListNode p2 = head;
while (p2!=null && p2 != p1 && p2.val < p1.val) {
prev = p2;
p2 = p2.next;
}

ListNode next = p1.next;

if(p2 == null){
prev.next = p1;
p1.next = null;
}else if (prev == null) {// head
p1.next = head;
head = p1;
}else {
p1.next = prev.next;
prev.next = p1;
}
p1 = next;
}

return head;
}

}