Say you have an array for which the ith element is the price of a given stock on day i.
If you were only permitted to complete at most one transaction (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit.
Note that you cannot sell a stock before you buy one.
Example 1:
Input: [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. Not 7-1 = 6, as selling price needs to be larger than buying price.
Example 2:
Input: [7,6,4,3,1] Output: 0 Explanation: In this case, no transaction is done, i.e. max profit = 0.
Source
def max_profit(prices):
if not prices:
return 0
profit = 0
min_price = prices[0]
for price in prices[1:]:
if price - min_price > profit:
profit = price - min_price
if price < min_price:
min_price = price
return profit
def max_profit(prices):
"""small variation"""
if not prices:
return 0
max_profit = 0
min_price = prices[0]
for price in prices[1:]:
if price < min_price:
min_price = price
profit = price - min_price
if profit > max_profit:
max_profit = profit
return max_profit
prices = [7,1,5,3,6,4]
max_profit(prices)
5
prices = [7,6,4,3,1]
max_profit(prices)
0
prices = [4, 6, 3, 8, 0, 6]
max_profit(prices)
6
prices = [4, 12, 0, 4]
max_profit(prices)
8