1 class FreqStack
2 {
3 public:
4 unordered_map<int,int> hash;
5 vector<int> stk;
6 int max_times;
7 int times_table[10001];
8 FreqStack()
9 {
10 memset(times_table,0,sizeof(times_table));
11 max_times = 0;
12 }
13
14 void push(int x)
15 {
16 stk.push_back(x);
17
18 auto ptr_to_hash = hash.find(x);
19 if(ptr_to_hash==hash.end())
20 {
21 hash.insert(make_pair(x,1));
22 times_table[1] ++;
23 max_times = max(1,max_times);
24 }
25 else
26 {
27 times_table[ptr_to_hash->second] --;
28 ptr_to_hash->second += 1;
29 times_table[ptr_to_hash->second] ++;
30 max_times = max(ptr_to_hash->second,max_times);
31 // cout << x << " " << max_times << endl;
32 }
33 }
34
35 int pop()
36 {
37 for(int i = stk.size()-1;i >= 0;i --)
38 {
39 auto ptr_to_hash = hash.find(stk[i]);
40 if(ptr_to_hash->second==max_times)
41 {
42 int result = stk[i];
43 stk.erase(stk.begin()+i);
44 times_table[ptr_to_hash->second] --;
45 ptr_to_hash->second -= 1;
46 times_table[ptr_to_hash->second] ++;
47 if(!times_table[max_times])
48 {
49 max_times --;
50 }
51 return result;
52 }
53 }
54 return max_times;
55 }
56 };
