63 股票最大利润

动态追踪当前最小值，当前最大利润和全局利润对比

class Solution:
    def largestprofit(self,A):
        if len(A) < 2:
            return 0
        min = A[0]
        res = max(A[1] - A[0],0)

        for i in range(2,len(A)):
            if A[i-1] < min:
                min = A[i-1]

            current = A[i] - min

            res = max(current,res)

        return res

S = Solution()
print(S.largestprofit([9,11,8,5,7,12,16,14]))