class Solution:
def maxProfit(self, prices) -> int:
l, r = prices[0], 0
for p in prices:
l, r = min(l, p), max(r, p - l)
return r
class Solution:
def maxProfit(self, prices) -> int:
l, r = prices[0], 0
for p in prices:
l, r = min(l, p), max(r, p - l)
return r