Stock date problem from Cassidoo newsletter

cassidoo_problem_08302020.py

'''
This week’s question:
Given an array of numbers that represent stock prices (where each number is the price for a certain day), find 2 days when you should buy and sell your stock for the highest profit.

Example:
$ stockBuySell([110, 180, 260, 40, 310, 535, 695])
$ “buy on day 4, sell on day 7”
'''

def stockBuySell(prices):
    buyDate = 0
    sellDate = 0
    buyPrice = prices[buyDate]
    sellPrice = prices[sellDate]
    profit = sellPrice - buyPrice
    best = (buyDate, sellDate, buyPrice, sellPrice, profit)

    while sellDate < len(prices) - 1:
        sellDate += 1
        sellPrice = prices[sellDate]
        if sellPrice < buyPrice:
            buyDate = sellDate
            buyPrice = prices[buyDate]
        profit = sellPrice - buyPrice

        if profit > best[4]:
            best = (buyDate, sellDate, buyPrice, sellPrice, profit)

    return best

def print_result(best):
    buyDate, sellDate, buyPrice, sellPrice, profit = best
    if profit == 0:
        print("No profit can be made, do not buy")
    else:
        print("Buy on day {} for {}, sell on day {} for {}, make {} in profit".format(buyDate + 1, sellDate + 1, buyPrice, sellPrice, profit))

if __name__ == "__main__":
    best = stockBuySell([0, 1, 2, 3, 4]) # Buy on day 1, sell on day 5
    print_result(best)

    best = stockBuySell([4, 3, 2, 1, 0]) # Don't buy
    print_result(best)

    best = stockBuySell([110, 180, 260, 40, 310, 535, 695]) # Buy on day 4, sell on day 7
    print_result(best)