题解 | #删除有序链表中重复的元素-I#基于哈希表

/**
 * struct ListNode {
 *  int val;
 *  struct ListNode *next;
 *  ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
#include <unordered_map>
class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        unordered_map<int, int> hashtable;
        ListNode* node = new ListNode(0);
        ListNode* p = node;
        while (head) {
            if (hashtable.find(head->val) == hashtable.end()) {
                hashtable[head->val] = 1;
                p->next = new ListNode(head->val);
                p = p->next;
            } else {
                head = head->next;
            }
        }
        return node->next;
    }
};