LC 981. Time Based Key-Value Store

Create a timebased key-value store class TimeMap , that supports two operations.

1. set(string key, string value, int timestamp)

• Stores the key and value , along with the given timestamp .

2. get(string key, int timestamp)

• Returns a value such that set(key, value, timestamp_prev) was called previously, with timestamp_prev <= timestamp .
• If there are multiple such values, it returns the one with the largest timestamp_prev .
• If there are no values, it returns the empty string ( "" ).

class TimeMap {

private:

  unordered_map<string, map<int, string>> mp;

  vector<int> tvec;

public:

  /** Initialize your data structure here. */

  TimeMap() {}

  void set(string key, string value, int timestamp) {

    mp[key][timestamp] = value;

  }

  string get(string key, int timestamp) {

    if(!mp.count(key)) return "";

    if(mp[key].count(timestamp)) return mp[key][timestamp];

    for(auto it = mp[key].rbegin(); it != mp[key].rend(); it++) {

      if(it->first > timestamp) continue;

      else {

        return it->second;

      }

    }

    return "";

  }

};