Implement FreqStack, a class which simulates the operation of a stack-like data structure.FreqStack has two functions:push(int x), which pushes an integer x onto the stack.pop(), which removes and returns the most frequent element in the stack.If there is a tie for most frequent element, the element closest to the top of the stack is removed and returned. Example 1:Input: ["FreqStack","push","push","push","push","push","push","pop","pop","pop","pop"],[[],[5],[7],[5],[7],[4],[5],[],[],[],[]]Output: [null,null,null,null,null,null,null,5,7,5,4]Explanation:After making six .push operations, the stack is [5,7,5,7,4,5] from bottom to top.  Then:pop() -> returns 5, as 5 is the most frequent.The stack becomes [5,7,5,7,4].pop() -> returns 7, as 5 and 7 is the most frequent, but 7 is closest to the top.The stack becomes [5,7,5,4].pop() -> returns 5.The stack becomes [5,7,4].pop() -> returns 4.The stack becomes [5,7]. Note:Calls to FreqStack.push(int x) will be such that 0 <= x <= 10^9.It is guaranteed that FreqStack.pop() won't be called if the stack has zero elements.The total number of FreqStack.push calls will not exceed 10000 in a single test case.The total number of FreqStack.pop calls will not exceed 10000 in a single test case.The total number of FreqStack.push and FreqStack.pop calls will not exceed 150000 across all test cases.

Hash map freq will count the frequence of elements.

Hash map m is a map of stack.

If element x has n frequence, we will push x n times in m[1], m[2] .. m[n]

maxfreq records the maximum frequence.

 

push(x) will push x tom[++freq[x]]

pop() will pop from the m[maxfreq]

 

 

class FreqStack {        HashMap
     
       map;    HashMap
      
       > freMap;    int mostFreq;    public FreqStack() {        map = new HashMap<>();        freMap = new HashMap<>();        mostFreq = 0;    }        public void push(int x) {        int freq = map.getOrDefault(x, 0)+1;        map.put(x, freq);        mostFreq = Math.max(mostFreq, freq);        if(!freMap.containsKey(freq)){            freMap.put(freq, new Stack
       
        ());                    }        freMap.get(freq).push(x);    }        public int pop() {        int x = freMap.get(mostFreq).pop();        map.put(x, mostFreq-1);        if(freMap.get(mostFreq).size() == 0){            freMap.remove(mostFreq);            mostFreq --;        }        return x;    }}/** * Your FreqStack object will be instantiated and called as such: * FreqStack obj = new FreqStack(); * obj.push(x); * int param_2 = obj.pop(); */