題目 : 121. Best Time to Buy and Sell Stock
You are given an array prices where prices[i] is the price of a given stock on the ith day.
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: 5
Explanation: 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: 0
Explanation: In this case, no transactions are done and the max profit = 0.
參考影片 : https://youtu.be/1pkOgXD63yU
class Solution:
def maxProfit(self, prices: List[int]) -> int:
l, r = 0 ,1 # Left=buy, Right=sell
# 0,1 分別代表索引值
maxP = 0 # 最高利潤值
while r < len(prices):
if prices[l] < prices[r] : # 如果左側l的金額<右側r的金額，代表可以買低賣高
profit = prices[r] - prices[l] # 計算利潤
maxP = max(maxP, profit) # 用max()回傳較大的數字到maxP，得到目前的最高利潤
else:
l = r
r += 1
return maxP
