<p>Given the <code>head</code> of a sorted linked list, <em>delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list</em>. Return <em>the linked list <strong>sorted</strong> as well</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/linkedlist1.jpg" style="width: 500px; height: 142px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,3,4,4,5]
<strong>Output:</strong> [1,2,5]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/04/linkedlist2.jpg" style="width: 500px; height: 205px;" />
<pre>
<strong>Input:</strong> head = [1,1,1,2,3]
<strong>Output:</strong> [2,3]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the list is in the range <code>[0, 300]</code>.</li>
	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
	<li>The list is guaranteed to be <strong>sorted</strong> in ascending order.</li>
</ul>

/**
 * Definition for singly-linked list.
 * 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) {
        map<int, int> mp;
        ListNode *p = head;
        while (p) {
            mp[p->val]++;
            p = p->next;
        }
        
        ListNode *head2 = nullptr, *tail = nullptr;
        for (auto &it : mp) {
            if (it.second == 1) {
                ListNode *node = new ListNode(it.first);
                if (!head2) {
                    head2 = node;
                    tail = head2;
                } else {
                    tail->next = node;
                    tail = tail->next;
                }
            }
        }
        return head2;  
    }
};
16800