All O`one Data Structure LeetCode solution in C++

1
class AllOne {
2
 public:
3
  map<int, unordered_set<string>> minmax;
4
  unordered_map<string, int> count;
5
  AllOne() {}
6

7
  void inc(string key) {
8
    int was = count[key]++;
9
    if (was > 0) {
10
      minmax[was].erase(key);
11
      if (minmax[was].size() == 0) minmax.erase(was);
12
    }
13
    minmax[was + 1].insert(key);
14
  }
15

16
  void dec(string key) {
17
    int was = count[key]--;
18
    minmax[was].erase(key);
19
    if (minmax[was].size() == 0) minmax.erase(was);
20
    if (was - 1 == 0) {
21
      count.erase(key);
22
    } else {
23
      minmax[was - 1].insert(key);
24
    }
25
  }
26

27
  string getMaxKey() {
28
    return minmax.size() == 0 ? "" : *minmax.rbegin()->second.begin();
29
  }
30

31
  string getMinKey() {
32
    return minmax.size() == 0 ? "" : *minmax.begin()->second.begin();
33
  }
34
};
35

36
/**
37
 * Your AllOne object will be instantiated and called as such:
38
 * AllOne* obj = new AllOne();
39
 * obj->inc(key);
40
 * obj->dec(key);
41
 * string param_3 = obj->getMaxKey();
42
 * string param_4 = obj->getMinKey();
43
 */