LeetCode 121

121. Best Time to Buy and Sell Stock

tip

Clicking the heading will take you to the LeetCode problem.

Solution

for loop

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        if not prices:
            return 0
            
        # Initialize two variables to store the minimum price and the maximum profit
        min_price = prices[0]
        max_profit = 0

        for index, price in enumerate(prices):
            if price < min_price:
                min_price = price
            else:
                profit = price - min_price
                if profit > max_profit:
                    max_profit = profit
        
        return max_profit

The time complexity is $O(n)$ because I iterate through the array only once. The space complexity is $O(1)$ because I use only two variables.