Leetcode 121: Best Time to Buy and Sell Stock

https://leetcode.com/problems/best-time-to-buy-and-sell-stock/

Say you have an array for which the i^th element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

 

Code

import sys

class Solution(object):
    def maxProfit(self, prices):
        """
        :type prices: List[int]
        :rtype: int
        """
        min_price = sys.maxint
        max_profit = 0
        for price in prices:
            min_price = min(min_price, price)
            max_profit = max(max_profit, price - min_price)
        
        return max_profit

 

Idea

`min_price` is the minimum price so far. The maximum profit must happen when `current price – min_price` is max.

 

Variant

If you are given difference array of prices, what would you do?
https://leetcode.com/discuss/48378/kadanes-algorithm-since-mentioned-about-interviewer-twists