Remove Duplicates from Sorted List II

题目：

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only
distinct numbers from the original list.

For example,

Given

1->2->3->3->4->4->5

, return

1->2->5

.

Given

1->1->1->2->3

, return

2->3

.

分析：先处理头指针，再处理重复问题。

代码如下：

ListNode *deleteDuplicates(ListNode *head) {

while(head!=NULL)

{

int i=0;

while(head->next!=NULL&&head->val==head->next->val)

{

head=head->next;

i++;

}

if(i>0)

{

head=head->next;

}

else

{

break;

}

}

if(head==NULL)return head;

if(head->next==NULL)return head;

ListNode *head1=head;

while(head1->next!=NULL)

{

ListNode *head2=head1->next;

int i=0;

while(head2->next!=NULL&&head2->next->val==head2->val)

{

head2=head2->next;

i++;

}

if(i>0)

{

head1->next=head2->next;

}

else

{

head1=head1->next;

}

}

return head;

}