gistfile1.txt

["StockPrice","update","maximum","current","minimum","maximum","maximum","maximum","minimum","minimum","maximum","update","maximum","minimum","update","maximum","minimum","current","maximum","update","minimum","maximum","update","maximum","maximum","current","update","current","minimum","update","update","minimum","minimum","update","current","update","maximum","update","minimum"]
[[],[38,2308],[],[],[],[],[],[],[],[],[],[47,7876],[],[],[58,1866],[],[],[],[],[43,121],[],[],[40,5339],[],[],[],[32,5339],[],[],[43,6414],[49,9369],[],[],[36,3192],[],[48,1006],[],[53,8013],[]]


output
[null,null,2308,2308,2308,2308,2308,2308,2308,2308,2308,null,7876,2308,null,7876,1866,1866,7876,null,121,7876,null,7876,7876,5339,null,5339,121,null,null,1866,1866,null,3192,null,9369,null,1006]

expected
[null,null,2308,2308,2308,2308,2308,2308,2308,2308,2308,null,7876,2308,null,7876,1866,1866,7876,null,121,7876,null,7876,7876,1866,null,1866,121,null,null,1866,1866,null,1866,null,9369,null,1006]


class StockPrice {
    
    TreeMap<Integer,Integer> timeToPrice;
    TreeMap<Integer,Set<Integer>> priceToTime;
    int current;

    public StockPrice() {
        timeToPrice = new TreeMap<>();   
        priceToTime = new TreeMap<>();
        current =0;
    }
    /*
        time price
       [1,5],
       [2,5],
       [1,6]
        
        price to time
        6 -> 1
        5 -> 2
        
        time to price
        1 -> 6
        2- > 5
        
        
    */
    
    public void update(int timestamp, int price) {
        
        if (timeToPrice.containsKey(timestamp)) {
            int priceToRemove = timeToPrice.get(timestamp);
            priceToTime.get(priceToRemove).remove(timestamp);
            if (priceToTime.get(priceToRemove).isEmpty()) priceToTime.remove(priceToRemove);
        } else {
            current = price;
        }
        timeToPrice.put(timestamp, price);          
        priceToTime.computeIfAbsent(price, s-> new HashSet<Integer>()).add(timestamp);
        
    }
    
    public int current() {
        return current;
    }
    
    public int maximum() {
        return priceToTime.lastKey();
    }
    
    public int minimum() {
        return priceToTime.firstKey();
    }
}