Leetcode 3433. Count Mentions Per User

• Leetcode 3433. Count Mentions Per User
  • 1. 解题思路
  • 2. 代码实现

• 题目链接：3433. Count Mentions Per User

1. 解题思路

这一题我们首先需要将所有的event按照时间顺序进行排序，然后就只需要记录一下每一个用户下一次在线的时间以及其总的被at的次数即可。

2. 代码实现

给出python代码实现如下：

class Solution:
    def countMentions(self, numberOfUsers: int, events: List[List[str]]) -> List[int]:
        events = sorted(events, key=lambda x: (int(x[1]), 0 if x[0] == "OFFLINE" else 1))
        status = [0 for _ in range(numberOfUsers)]
        cnt = [0 for _ in range(numberOfUsers)]
        for event in events:
            t = int(event[1])
            if event[0] == "MESSAGE":
                mention = event[2]
                if mention == "ALL":
                    cnt = [x+1 for x in cnt]
                elif mention == "HERE":
                    cnt = [x+1 if t >= st else x for x, st in zip(cnt, status)]
                else:
                    for uid in mention.split(" "):
                        cnt[int(uid[2:])] += 1
            else:
                uid = int(event[2])
                status[uid] = t + 60
        return cnt    

提交代码评测得到：耗时38ms，占用内存18MB。