Leetcode-121题:Best Time to Buy a

题目

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.

思路

只需访问到当前元素时知道它之前的最小元素即可。

代码

class Solution:
    # @param {integer[]} prices
    # @return {integer}
    def maxProfit(self, prices):
        if prices==None or len(prices)==0:
            return 0
        cur_min = prices[0]
        max_profit = 0
        for price in prices:
            if price < cur_min:
                cur_min = price
            elif price-cur_min > max_profit:
                max_profit = price-cur_min
        return max_profit