121. Best Time to Buy and Sell Stock
- 描述：
- 思路：
[1,2,3,4] ==> returns 3 (buy at 1 and sell at 4)
[4,3,2,1] ==> returns 0 (don't buy)
[4,10,25,2,10] ==> returns 21 (buy at 4 and sell at 25)
遍历每天的价格，与当前最低价格相比较min_price;然后当前价格减去最低价格，算出当前利润profit；当前利润与最大利润相比较，得出结果。
- 代码
class Solution:
def maxProfit(self, prices):
"""
:type prices: List[int]
:rtype: int
"""
max_profit, min_price = 0, float('inf')
for price in prices:
min_price=min(min_price,price)
profit=price-min_price
max_profit=max(max_profit,profit)
return max_profit
