1.题目描述
Given a sorted linked list, delete all duplicates such that each element appear only once.
给定一个排序链表，删除所有重复的元素，使得每个元素只出现一次。
Example 1:
Input: 1->1->2
Output: 1->2
Example 2:
Input: 1->1->2->3->3
Output: 1->2->3
2.Solutions
类似于82题解决思路：
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public static ListNode (ListNode head) {
if(head == null || head.next == null) return head;
ListNode dummy=new ListNode(0);
dummy.next=head;
ListNode pre=dummy;
ListNode cur=head;
while(cur!=null){
while(cur.next!=null&&cur.val==cur.next.val){
cur=cur.next;
}
if(pre.next==cur)
pre=pre.next;
else{
pre.next=cur;
pre=pre.next;
}
cur=cur.next;
}
return dummy.next;
}
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单指针：
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public static ListNode (ListNode head) {
if(head == null || head.next == null)
return head;
ListNode cur = head;
while(cur.next != null){
if(cur.next == null)
break;
if(cur.val == cur.next.val)
cur.next = cur.next.next;
else
cur = cur.next;
}
return head;
}
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递归：
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public ListNode (ListNode head) {
if(head == null || head.next == null)return head;
head.next = deleteDuplicates(head.next);
return head.val == head.next.val ? head.next : head;
}
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（完）
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