0121 Best Time to Buy and Sell Stock

Solved at: 2022-07-13

Question

You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

Solution

python

class Solution:    def maxProfit(self, prices: List[int]) -> int:        if not prices:            return 0        minv = prices[0]        profit = 0        for i, price in enumerate(prices):            if price < minv:                minv = price            else:                if profit < prices[i] - minv:                    profit = prices[i] - minv        return profit

class Solution:    def maxProfit(self, prices: List[int]) -> int:        if not prices:            return 0        minv = prices[0]        profit = 0        for i, price in enumerate(prices):            if price < minv:                minv = price            else:                if profit < prices[i] - minv:                    profit = prices[i] - minv        return profit

I had to get a hint to keep the minimum value so far.

Time Complexity: $O(n)$
Space Complexity: $O(1)$

Results

Runtime

1698 ms, faster than 38.38% of Python3 online submissions for Best Time to Buy and Sell Stock.

Memory Usage

25 MB, less than 37.97% of Python3 online submissions for Best Time to Buy and Sell Stock.