private static class P50Calculator {
        final PriorityQueue<Integer> minHeap;
        final PriorityQueue<Integer> maxHeap;
        public P50Calculator(){
            minHeap = new PriorityQueue<>(new Comparator<Integer>() {
                @Override
                public int compare(Integer num1, Integer num2) {
                    return num2 - num1;
                }
            });
            maxHeap = new PriorityQueue<>();
        }

        public void addValue(int value) {
            if(minHeap.isEmpty() || value<minHeap.peek()){
                minHeap.offer(value);
            } else {
                maxHeap.offer(value);
            }
            final PriorityQueue<Integer> heap1 = minHeap.size()>=maxHeap.size() ? minHeap : maxHeap;
            final PriorityQueue<Integer> heap2 = minHeap.size()<=maxHeap.size() ? minHeap : maxHeap;
            if((heap1.size()-heap2.size())>1){
                heap2.offer(heap1.poll());
            }
        }

        public double getP50(){
            if(minHeap.size()==maxHeap.size()){
                return minHeap.size()==0 ? 0 : (minHeap.peek() + maxHeap.peek())/2.0;
            }
            return minHeap.size() > maxHeap.size() ? minHeap.peek() : maxHeap.peek();
        }
    }