Maximum Frequency Stack LeetCode solution in C++

1
class FreqStack {
2
 public:
3
  unordered_map<int, int> ump;
4
  unordered_map<int, stack<int>> ump_st;
5

6
  int cap = 1;
7

8
  FreqStack() {
9
    ump.clear();
10
    ump_st.clear();
11
  }
12

13
  void push(int val) {
14
    // increasing the count
15
    if (ump.find(val) != ump.end()) {
16
      ump[val]++;
17
    } else {
18
      ump[val] = 1;
19
    }
20

21
    // update the highest level
22
    if (cap < ump[val]) {
23
      cap = ump[val];
24
    }
25

26
    // push the elements in the stack where it belongs as per height
27
    ump_st[ump[val]].push(val);
28
  }
29

30
  int pop() {
31
    int val = ump_st[cap].top();
32
    ump_st[cap].pop();
33

34
    if (ump_st[cap].size() == 0) {
35
      cap--;
36
    }
37

38
    ump[val]--;
39

40
    if (ump[val] == 0) {
41
      ump.erase(val);
42
    }
43

44
    return val;
45
  }
46
};