链表相关面试题

public  ListNode insertionSortList(ListNode head) {

if (head == null) {
return head;
}

ListNode toInsert = head;
ListNode newHead = null;

while (toInsert != null) {

ListNode cur = newHead;
ListNode next = toInsert.next;

// 判断头部
if (cur == null||toInsert.val <= newHead.val) {

toInsert.next = cur;
newHead = toInsert;

} else {

while (cur.next != null) {

if (cur.val <= toInsert.val && toInsert.val <= cur.next.val) {

toInsert.next = cur.next;
cur.next = toInsert;
break;
}
cur =cur.next;

}
//如果待插入的数是最大的，就把它放在后面
if (cur.next == null) {
cur.next = toInsert;
toInsert.next = null;
}

}

toInsert = next;
}

return newHead;

}