# 删除排序链表中的重复元素

<p>存在一个按升序排列的链表，给你这个链表的头节点 <code>head</code> ，请你删除所有重复的元素，使每个元素 <strong>只出现一次</strong> 。</p><p>返回同样按升序排列的结果链表。</p><p> </p><p><strong>示例 1：</strong></p><img alt="" src="https://cdn.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0083.Remove%20Duplicates%20from%20Sorted%20List/images/list1.jpg" style="width: 302px; height: 242px;" /><pre><strong>输入：</strong>head = [1,1,2]<strong><br />输出：</strong>[1,2]</pre><p><strong>示例 2：</strong></p><img alt="" src="https://cdn.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0083.Remove%20Duplicates%20from%20Sorted%20List/images/list2.jpg" style="width: 542px; height: 222px;" /><pre><strong>输入：</strong>head = [1,1,2,3,3]<strong><br />输出：</strong>[1,2,3]</pre><p> </p><p><strong>提示：</strong></p><ul>	<li>链表中节点数目在范围 <code>[0, 300]</code> 内</li>	<li><code>-100 <= Node.val <= 100</code></li>	<li>题目数据保证链表已经按升序排列</li></ul>

## template

```cpp
#include <bits/stdc++.h>
using namespace std;
struct ListNode
{
	int val;
	ListNode *next;
	ListNode() : val(0), next(nullptr) {}
	ListNode(int x) : val(x), next(nullptr) {}
	ListNode(int x, ListNode *next) : val(x), next(next) {}
};
class Solution
{
public:
	ListNode *deleteDuplicates(ListNode *head)
	{
		if (head == nullptr)
		{
			return nullptr;
		}
		ListNode *prev = head;
		ListNode *p = prev->next;
		while (p != nullptr)
		{
			if (p->val != prev->val)
			{
				prev->next = p;
				prev = p;
			}
			p = p->next;
		}
		prev->next = p;
		return head;
	}
};
```

## 答案

```cpp

```

## 选项

### A

```cpp

```

### B

```cpp

```

### C

```cpp

```