买卖股票的最佳时机

def solve():
    def maxProfit(prices):
        min_price = float('inf')
        max_profit = 0
        for price in prices:
            min_price = min(min_price, price)
            max_profit = max(max_profit, price - min_price)
        return max_profit
    print(maxProfit([7, 1, 5, 3, 6, 4]))