Eric 的小站

1
输入：head = [1,2,3,3,4,4,5]
2
输出：[1,2,5]

1
输入：head = [1,1,1,2,3]
2
输出：[2,3]

1
/**
2
 * Definition for singly-linked list.
3
 * struct ListNode {
4
 *     int val;
5
 *     ListNode *next;
6
 *     ListNode() : val(0), next(nullptr) {}
7
 *     ListNode(int x) : val(x), next(nullptr) {}
8
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
9
 * };
10
 */
11
class Solution {
12
public:
13
    ListNode* deleteDuplicates(ListNode* head) {
14
        if (head == nullptr)
15
            return head;
16
        ListNode* result = new ListNode();
17
        unordered_map<int, int> Map;
18
        ListNode *p = head, *q = result;
19
        while (p) {
20
            Map[p->val]++;
21
            p = p->next;
22
        }
23
        p = head;
24
        while (p) {
25
            if (Map[p->val] == 1) {
26
                q->next = new ListNode(p->val);
27
                q = q->next;
28
            }
29
            p = p->next;
30
        }
31
        return result->next;
32
    }
33
};