best-time-to-buy-and-sell-stock.py

# Time:  O(n)
# Space: O(1)
#
# Say you have an array for which the ith element 
# is the price of a given stock on day i.
#
# If you were only permitted to complete at most one transaction 
# (ie, buy one and sell one share of the stock), 
# design an algorithm to find the maximum profit.
#

class Solution:
    # @param prices, a list of integer
    # @return an integer
    def maxProfit(self, prices):
        max_profit, min_price = 0, float("inf")
        for price in prices:
            min_price = min(min_price, price)
            max_profit = max(max_profit, price - min_price)  
        return max_profit

if __name__ == "__main__":
    result = Solution().maxProfit([3, 2, 1, 4, 2, 5, 6])
    print result