CareerCup 2.1

最新推荐文章于 2017-12-01 17:21:00 发布

原创最新推荐文章于 2017-12-01 17:21:00 发布 · 532 阅读

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本文介绍了一种从无序链表中去除重复元素的方法，并提供了两种实现方式：一种使用辅助哈希表来提高效率；另一种则完全不使用额外空间，通过双指针技巧完成任务。

2.1 Write code to remove duplicates from an unsorted linked list.

FOLLOW UP

How would you solve this problem if a temporary buffer is not allowed?

struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};

void deleteDups(ListNode *head) {
    if (head) {
        map<int, bool> table;
        ListNode *current = head;
        ListNode *prevous = NULL;
        while (current) {
            if (table.find(current->val) != table.end()) {
                prevous->next = current->next;
            } else {
                table.insert(pair<int, bool>(current->val, true));
                prevous = current;
            }
            current = current->next;
        }
    }
}

Follow up:

void deleteDups(ListNode *head) {
    if (head) {
        ListNode *current = head;
        while (current) {
            ListNode *runner = current;
            while (runner->next) {
                if (current->val == runner->next->val) {
                    runner->next = runner->next->next;
                } else {
                    runner = runner->next;
                }
            }
            current = current->next;
        }
    }
}