Stock Span - Amazon Top Interview Questions


Problem Statement :


Implement a data structure simulating a stock ticker which implements the following method:

int next(int price) is called once per day and sets the stock price for today to price. It returns the number of consecutive days from today and prior where the price of the stock was less than or equal to price.

Constraints

0 ≤ n ≤ 100,000 where n is the number of calls to next

Example 1

Input

methods = ["constructor", "next", "next", "next", "next", "next"]
arguments = [[], [1], [3], [2], [5], [7]]`

Output

[None, 1, 2, 1, 4, 5]

Explanation

s = StockSpan()
s.next(1) == 1
s.next(3) == 2
s.next(2) == 1
s.next(5) == 4
s.next(7) == 5


Solution :



title-img 




                        Solution in C++ :

class StockSpan {
    public:
    int idx = 0;
    stack<pair<int, int>> s;
    int next(int price) {
        while (!s.empty() and s.top().first <= price) s.pop();
        int ans = s.empty() ? idx : idx - s.top().second;
        s.push({price, ++idx});
        return ans + 1;
    }
};
                    




                        Solution in Python : 
                            
class StockSpan:
    def __init__(self):
        self.stk = []
        self.d = 0

    def next(self, price):
        self.d += 1
        while self.stk and price >= self.stk[-1][0]:
            self.stk.pop()
        ret = self.d if not self.stk else self.d - self.stk[-1][1]
        self.stk += ((price, self.d),)
        return ret


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