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feat: add solutions to lc problem: No.3433 (#4005)
No.3433.Count Mentions Per User
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‎solution/3400-3499/3433.Count Mentions Per User/README.md

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<!-- solution:start -->
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### 方法一
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### 方法一：排序 + 模拟
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我们将事件按照时间戳升序排序，如果时间戳相同，我们将 OFFLINE 事件排在 MESSAGE 事件之前。
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然后我们模拟事件的发生过程，使用 `online_t` 数组记录每个用户下一次上线的时间，用一个变量 `lazy` 记录所有用户还需要被提及的次数。
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遍历事件列表，根据事件类型进行处理：
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- 如果是 ONLINE 事件，我们更新 `online_t` 数组；
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- 如果是 ALL 事件，我们将 `lazy` 加一；
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- 如果是 HERE 事件，我们遍历 `online_t` 数组，如果用户下一次上线的时间小于等于当前时间，我们将该用户的提及次数加一；
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- 如果是 MESSAGE 事件，我们将提及的用户的提及次数加一。
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最后，如果 `lazy` 大于 0，我们将所有用户的提及次数加上 `lazy`。
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时间复杂度 $O(n + m \times \log m \log M + L)$，空间复杂度 $O(n)$。其中 $n$ 和 $m$ 分别是用户总数和事件总数，而 $M$ 和 $L$ 分别是时间戳的最大值以及所有提及的字符串的总长度。
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<!-- tabs:start -->
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#### Python3
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```python
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class Solution:
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def countMentions(self, numberOfUsers: int, events: List[List[str]]) -> List[int]:
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events.sort(key=lambda e: (int(e[1]), e[0][2]))
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ans = [0] * numberOfUsers
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online_t = [0] * numberOfUsers
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lazy = 0
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for etype, ts, s in events:
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cur = int(ts)
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if etype[0] == "O":
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online_t[int(s)] = cur + 60
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elif s[0] == "A":
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lazy += 1
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elif s[0] == "H":
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for i, t in enumerate(online_t):
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if t <= cur:
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ans[i] += 1
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else:
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for a in s.split():
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ans[int(a[2:])] += 1
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if lazy:
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for i in range(numberOfUsers):
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ans[i] += lazy
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return ans
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```
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#### Java
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```java
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class Solution {
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public int[] countMentions(int numberOfUsers, List<List<String>> events) {
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events.sort((a, b) -> {
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int x = Integer.parseInt(a.get(1));
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int y = Integer.parseInt(b.get(1));
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if (x == y) {
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return a.get(0).charAt(2) - b.get(0).charAt(2);
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}
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return x - y;
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});
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int[] ans = new int[numberOfUsers];
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int[] onlineT = new int[numberOfUsers];
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int lazy = 0;
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for (var e : events) {
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String etype = e.get(0);
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int cur = Integer.parseInt(e.get(1));
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String s = e.get(2);
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if (etype.charAt(0) == 'O') {
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onlineT[Integer.parseInt(s)] = cur + 60;
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} else if (s.charAt(0) == 'A') {
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++lazy;
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} else if (s.charAt(0) == 'H') {
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for (int i = 0; i < numberOfUsers; ++i) {
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if (onlineT[i] <= cur) {
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++ans[i];
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}
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}
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} else {
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for (var a : s.split(" ")) {
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++ans[Integer.parseInt(a.substring(2))];
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}
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}
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}
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if (lazy > 0) {
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for (int i = 0; i < numberOfUsers; ++i) {
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ans[i] += lazy;
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}
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}
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return ans;
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}
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}
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```
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#### C++
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```cpp
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class Solution {
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public:
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vector<int> countMentions(int numberOfUsers, vector<vector<string>>& events) {
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ranges::sort(events, [](const vector<string>& a, const vector<string>& b) {
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int x = stoi(a[1]);
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int y = stoi(b[1]);
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if (x == y) {
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return a[0][2] < b[0][2];
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}
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return x < y;
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});
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vector<int> ans(numberOfUsers, 0);
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vector<int> onlineT(numberOfUsers, 0);
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int lazy = 0;
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for (const auto& e : events) {
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string etype = e[0];
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int cur = stoi(e[1]);
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string s = e[2];
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if (etype[0] == 'O') {
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onlineT[stoi(s)] = cur + 60;
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} else if (s[0] == 'A') {
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lazy++;
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} else if (s[0] == 'H') {
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for (int i = 0; i < numberOfUsers; ++i) {
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if (onlineT[i] <= cur) {
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++ans[i];
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}
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}
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} else {
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stringstream ss(s);
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string token;
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while (ss >> token) {
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ans[stoi(token.substr(2))]++;
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}
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}
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}
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if (lazy > 0) {
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for (int i = 0; i < numberOfUsers; ++i) {
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ans[i] += lazy;
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}
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}
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return ans;
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}
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};
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```
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#### Go
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```go
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func countMentions(numberOfUsers int, events [][]string) []int {
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sort.Slice(events, func(i, j int) bool {
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x, _ := strconv.Atoi(events[i][1])
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y, _ := strconv.Atoi(events[j][1])
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if x == y {
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return events[i][0][2] < events[j][0][2]
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}
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return x < y
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})
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ans := make([]int, numberOfUsers)
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onlineT := make([]int, numberOfUsers)
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lazy := 0
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for _, e := range events {
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etype := e[0]
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cur, _ := strconv.Atoi(e[1])
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s := e[2]
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if etype[0] == 'O' {
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userID, _ := strconv.Atoi(s)
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onlineT[userID] = cur + 60
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} else if s[0] == 'A' {
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lazy++
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} else if s[0] == 'H' {
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for i := 0; i < numberOfUsers; i++ {
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if onlineT[i] <= cur {
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ans[i]++
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}
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}
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} else {
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mentions := strings.Split(s, " ")
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for _, m := range mentions {
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userID, _ := strconv.Atoi(m[2:])
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ans[userID]++
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}
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}
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}
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if lazy > 0 {
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for i := 0; i < numberOfUsers; i++ {
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ans[i] += lazy
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}
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}
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return ans
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}
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```
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#### TypeScript
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```ts
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function countMentions(numberOfUsers: number, events: string[][]): number[] {
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events.sort((a, b) => {
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const x = +a[1];
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const y = +b[1];
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if (x === y) {
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return a[0].charAt(2) < b[0].charAt(2) ? -1 : 1;
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}
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return x - y;
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});
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const ans: number[] = Array(numberOfUsers).fill(0);
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const onlineT: number[] = Array(numberOfUsers).fill(0);
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let lazy = 0;
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for (const [etype, ts, s] of events) {
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const cur = +ts;
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if (etype.charAt(0) === 'O') {
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const userID = +s;
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onlineT[userID] = cur + 60;
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} else if (s.charAt(0) === 'A') {
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lazy++;
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} else if (s.charAt(0) === 'H') {
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for (let i = 0; i < numberOfUsers; i++) {
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if (onlineT[i] <= cur) {
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ans[i]++;
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}
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}
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} else {
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const mentions = s.split(' ');
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for (const m of mentions) {
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const userID = +m.slice(2);
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ans[userID]++;
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}
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}
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}
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if (lazy > 0) {
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for (let i = 0; i < numberOfUsers; i++) {
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ans[i] += lazy;
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}
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}
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return ans;
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}
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```
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<!-- tabs:end -->

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