给定一个数组，它的第 i 个元素是一支给定股票第 i 天的价格。(第一个我理解错了,然后看了以前代码,第二三个我跟根据官网改编的,最后的几个你猜啊)
class Solution(object):
def maxProfit1(self, prices):
"""
:type prices: List[int]
:rtype: int
"""
length = len(prices)
if not prices or length < 2:
return 0
dp = [[0, 0] for i in range(length)]
dp[0][1] = -prices[0]
print(dp)
for i in range(1, length):
dp[i][0] = max(dp[i-1][1] + prices[i], dp[i-1][0])
dp[i][1] = max(dp[i-1][1], dp[i-1][0] - prices[i])
return dp[length-1][0]
def maxProfit1(self, prices):
length = len(prices)
if not prices or length < 2:
return 0
ret = 0
for i in range(length):
for j in range(i + 1, length):
ret = max(ret, prices[j] - prices[i])
return ret
def maxProfit2(self, prices):
"""
maxProfit3我感觉他的第二种方式比较难理解所以改造一下
把第一天和第二天的给跳过,假设第一天就是最低价格,最大价值就是第二天减去第一天,然后其他的在循环中进行
"""
length = len(prices)
if not prices or length < 2:
return 0
min_price = prices[0]
max_profit = prices[1] - min_price
for i in range(2, length + 1):
min_price = min(prices[i - 1], min_price)
max_profit = max(prices[i - 1] - min_price, max_profit)
return max_profit
def maxProfit3(self, prices) -> int:
inf = int(1e9)
minprice = inf
maxprofit = 0
for price in prices:
maxprofit = max(price - minprice, maxprofit)
minprice = min(price, minprice)
return maxprofit
def maxProfit(self, prices):
if prices == []:
return 0
small = prices[0]
res = 0
for x in prices:
if x > small+res:
res = x-small
continue
if x < small:
small = x
continue
return res
if __name__ == '__main__':
s = Solution()
prices = [7, 1, 5, 3, 6, 4]
prices = [7, 1]
print(s.maxProfit(prices))