動機
經典的stock系列題目的開始
Problem
You are given an array prices
where prices[i]
is the price of a given stock on the ith
day.
You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.
Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0
.
Example 1:
Input: prices = [7,1,5,3,6,4]Output: 5Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.
Example 2:
Input: prices = [7,6,4,3,1]Output: 0Explanation: In this case, no transactions are done and the max profit = 0.
Constraints:
1 <= prices.length <= 105
0 <= prices[i] <= 104
Sol
只能做一次就從最小的去算
class Solution:
def maxProfit(self, prices: List[int]) -> int:
small = math.inf
ret = 0
for p in prices:
small = min(small, p)
ret = max(ret, p-small)
return ret