121_Best_Time_to_Buy_and_Sell_Stock.py

# 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.

 

# Example 1:

# Input: prices = [7,1,5,3,6,4]
# Output: 5
# Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
# Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.
# Example 2:

# Input: prices = [7,6,4,3,1]
# Output: 0
# Explanation: In this case, no transactions are done and the max profit = 0.
 

# Constraints:

# 1 <= prices.length <= 105
# 0 <= prices[i] <= 104

class Solution:
    def maxProfit(self, prices: list[int]) -> int:
        min_price = prices[0]
        max_profit = 0

        for price in prices:

            if price < min_price:
                min_price = price

            current_profit = price - min_price

            if current_profit > max_profit:
                max_profit = current_profit
            
        return max_profit