Question

1604. Alert Using Same Key-Card Three or More Times in a One Hour Period

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Description

LeetCode company workers use key-cards to unlock office doors. Each time a worker uses their key-card, the security system saves the worker's name and the time when it was used. The system emits an alert if any worker uses the key-card three or more times in a one-hour period.

You are given a list of strings keyName and keyTime where [keyName[i], keyTime[i]] corresponds to a person's name and the time when their key-card was used in a single day.

Access times are given in the 24-hour time format "HH:MM", such as "23:51" and "09:49".

Return a _list of unique worker names who received an alert for frequent keycard use_. Sort the names in ascending order alphabetically.

Notice that "10:00" - "11:00" is considered to be within a one-hour period, while "22:51" - "23:52" is not considered to be within a one-hour period.

 

Example 1:

Input: keyName = ["daniel","daniel","daniel","luis","luis","luis","luis"], keyTime = ["10:00","10:40","11:00","09:00","11:00","13:00","15:00"]
Output: ["daniel"]
Explanation: "daniel" used the keycard 3 times in a one-hour period ("10:00","10:40", "11:00").

Example 2:

Input: keyName = ["alice","alice","alice","bob","bob","bob","bob"], keyTime = ["12:01","12:00","18:00","21:00","21:20","21:30","23:00"]
Output: ["bob"]
Explanation: "bob" used the keycard 3 times in a one-hour period ("21:00","21:20", "21:30").

 

Constraints:

• 1 <= keyName.length, keyTime.length <= 105
• keyName.length == keyTime.length
• keyTime[i] is in the format "HH:MM".
• [keyName[i], keyTime[i]] is unique.
• 1 <= keyName[i].length <= 10
• keyName[i] contains only lowercase English letters.

Solutions

Solution 1

class Solution:
  def alertNames(self, keyName: List[str], keyTime: List[str]) -> List[str]:
    d = defaultdict(list)
    for name, t in zip(keyName, keyTime):
      t = int(t[:2]) * 60 + int(t[3:])
      d[name].append(t)
    ans = []
    for name, ts in d.items():
      if (n := len(ts)) > 2:
        ts.sort()
        for i in range(n - 2):
          if ts[i + 2] - ts[i] <= 60:
            ans.append(name)
            break
    ans.sort()
    return ans

class Solution {
  public List<String> alertNames(String[] keyName, String[] keyTime) {
    Map<String, List<Integer>> d = new HashMap<>();
    for (int i = 0; i < keyName.length; ++i) {
      String name = keyName[i];
      String time = keyTime[i];
      int t
        = Integer.parseInt(time.substring(0, 2)) * 60 + Integer.parseInt(time.substring(3));
      d.computeIfAbsent(name, k -> new ArrayList<>()).add(t);
    }
    List<String> ans = new ArrayList<>();
    for (var e : d.entrySet()) {
      var ts = e.getValue();
      int n = ts.size();
      if (n > 2) {
        Collections.sort(ts);
        for (int i = 0; i < n - 2; ++i) {
          if (ts.get(i + 2) - ts.get(i) <= 60) {
            ans.add(e.getKey());
            break;
          }
        }
      }
    }
    Collections.sort(ans);
    return ans;
  }
}

class Solution {
public:
  vector<string> alertNames(vector<string>& keyName, vector<string>& keyTime) {
    unordered_map<string, vector<int>> d;
    for (int i = 0; i < keyName.size(); ++i) {
      auto name = keyName[i];
      auto time = keyTime[i];
      int a, b;
      sscanf(time.c_str(), "%d:%d", &a, &b);
      int t = a * 60 + b;
      d[name].emplace_back(t);
    }
    vector<string> ans;
    for (auto& [name, ts] : d) {
      int n = ts.size();
      if (n > 2) {
        sort(ts.begin(), ts.end());
        for (int i = 0; i < n - 2; ++i) {
          if (ts[i + 2] - ts[i] <= 60) {
            ans.emplace_back(name);
            break;
          }
        }
      }
    }
    sort(ans.begin(), ans.end());
    return ans;
  }
};

func alertNames(keyName []string, keyTime []string) (ans []string) {
  d := map[string][]int{}
  for i, name := range keyName {
    var a, b int
    fmt.Sscanf(keyTime[i], "%d:%d", &a, &b)
    t := a*60 + b
    d[name] = append(d[name], t)
  }
  for name, ts := range d {
    n := len(ts)
    if n > 2 {
      sort.Ints(ts)
      for i := 0; i < n-2; i++ {
        if ts[i+2]-ts[i] <= 60 {
          ans = append(ans, name)
          break
        }
      }
    }
  }
  sort.Strings(ans)
  return
}