LC 901. Online Stock Span

Write a class StockSpanner which collects daily price quotes for some stock, and returns the span of that stock's price for the current day.

The span of the stock's price today is defined as the maximum number of consecutive days (starting from today and going backwards) for which the price of the stock was less than or equal to today's price.

For example, if the price of a stock over the next 7 days were [100, 80, 60, 70, 60, 75, 85], then the stock spans would be [1, 1, 1, 2, 1, 4, 6].

Example 1:

Input: ["StockSpanner","next","next","next","next","next","next","next"], [[],[100],[80],[60],[70],[60],[75],[85]]
Output: [null,1,1,1,2,1,4,6]
Explanation: 
First, S = StockSpanner() is initialized.  Then:
S.next(100) is called and returns 1,
S.next(80) is called and returns 1,
S.next(60) is called and returns 1,
S.next(70) is called and returns 2,
S.next(60) is called and returns 1,
S.next(75) is called and returns 4,
S.next(85) is called and returns 6.

Note that (for example) S.next(75) returned 4, because the last 4 prices
(including today's price of 75) were less than or equal to today's price.

Note:

1. Calls to StockSpanner.next(int price) will have 1 <= price <= 10^5.
2. There will be at most 10000 calls to StockSpanner.next per test case.
3. There will be at most 150000 calls to StockSpanner.next across all test cases.
4. The total time limit for this problem has been reduced by 75% for C++, and 50% for all other languages.

 

Runtime: 225 ms, faster than 32.65% of Java online submissions for Online Stock Span.

class StockSpanner {
  private Stack<Integer> s;
  private List<Integer> alist;
  private int cnt;
  public StockSpanner() {
    s = new Stack<>();
    alist = new ArrayList<>();
    cnt = 0;
  }

  public int next(int price) {
    while( !s.empty() && alist.get(s.peek()) <= price ){
      s.pop();
    }
    int tmpval;
    if(!s.empty()) tmpval = s.peek();
    else tmpval = -1;
    s.add(cnt);
    alist.add(price);
    cnt++;
    return s.peek() - tmpval;
  }
}

another solution

class StockSpanner {
        List<Stock> stocks = new ArrayList<>();
    public StockSpanner() {
//        prices = new ArrayList<>();
//        counts = new ArrayList<>();
    }

    public int next(int price) {
        
        

        // Need to search backwards for the next highest price
        int count = 1;
        // int countIndex = size-1;

//        int countIndex = size-1;
        while(stocks.size() >= count) {
           Stock s = stocks.get(stocks.size() - count);
            if (s.price > price) {
                break;
            } else {
                count += s.count;
            }
        }
        stocks.add(new Stock(price, count));
//        counts.add(count);
        return count;
    }

    class Stock {
        int price;
        int count;

        public Stock(final int price, final int count) {
            this.price = price;
            this.count = count;
        }
    }

}