buyAndSellStock.py

# Best Time to Buy and Sell Stock [Leetcode problem]

# 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.

# Answer

def maxProfit(prices):
    buy = 0
    sell = 1
    maxProfit = 0

    while sell < len(prices):
        if prices[sell] > prices[buy]:
            profit = prices[sell] - prices[buy]
            maxProfit = max(profit, maxProfit)
        else:
            buy = sell
        
        sell = sell + 1

    return maxProfit


prices = [7,1,5,3,6,4]
print(maxProfit(prices))