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.
Example 1:
Input: [7, 1, 5, 3, 6, 4] Output: 5 max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)
Example 2:
Input: [7, 6, 4, 3, 1] Output: 0 In this case, no transaction is done, i.e. max profit = 0.
自己写的~~
1 class Solution(object): 2 def maxProfit(self, prices): 3 """ 4 :type prices: List[int] 5 :rtype: int 6 """ 7 if prices == []: 8 return 0 9 buy = prices[0] 10 profit = 0 11 i=1 12 while i < len(prices): 13 sell = prices[i] 14 cur = sell-buy 15 if cur < 0: 16 buy= sell 17 i = i+1 18 elif profit < cur: 19 profit = cur 20 i=i+1 21 else: 22 i = i+1 23 24 return profit
1 class Solution(object): 2 def maxProfit(self, prices): 3 """ 4 :type prices: List[int] 5 :rtype: int 6 """ 7 max_profit, min_price = 0, float('inf') 8 for price in prices: 9 min_price = min(min_price, price) 10 profit = price - min_price 11 max_profit = max(max_profit, profit) 12 return max_profit
float("inf")正无穷
float("-inf")负无穷
