删除单链表内的重复节点

1. LeetCode 83. Remove Duplicates from Sorted List

2. 描述:

给定一个有序链表，删除其中的重复元素，使得每个元素都只出现一次。

3. 解决方案1：迭代法

ListNode* DeleteDuplicates(ListNode* head){
    if(head == nullptr || head->next == nullptr){
        return head;
    }
    ListNode* cur = head;
    while(cur != nullptr){
        while(cur->next != nullptr && cur->next->val == cur->val){
            ListNode* next_node = cur->next;
            cur->next = next_node->next;
            delete next_node;
        }
        cur = cur->next;
    }
    return head;
}

4. 解决方案2：递归法

ListNode* DeleteDuplicates(ListNode* head){
    if(head == nullptr || head->next == nullptr){
        return head;
    }
    head->next = DeleteDuplicates(head->next);
    return head->next->val == head->val ? head->next : head;
}