[Solved] Maximum Profit by Buying and Selling Stocks Shares

Coding challenge: You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

This coding question was asked in the HackerEarth coding interview.

Solution

You don’t need any fancy data structure or algorithm to solve this problem. Stick with a basic array/list and some conditional checks.

Prerequisite:

• Python list
• Python loop

Python code:

def return_max_profit(prices):
    out = 0
    curr_buy = prices[0]
    i=1
    while i < len(prices)-1:
        if prices[i] < curr_buy:
            curr_buy = prices[i]
            i+=1
        else:
            if prices[i] > prices[i+1]:
                print(f"Buy at {curr_buy} & sell at {prices[i]}.")
                out += (prices[i]-curr_buy)
                curr_buy = prices[i+1]
                i+=2
            else:
                i+=1
    return out


prices = [7,1,5,3,6,4]
print(f"Maximum Profit: {return_max_profit(prices)}")

Output:

Buy at 1 & sell at 5.
Buy at 3 & sell at 6.
Maximum Profit: 7

The code looks self-explanatory. Still, if you have any doubts, let’s discuss them in the comment section below.

Try to solve this coding challenge in any other programming language like C/C++, Java, etc. And share your solution with others here.

Aniruddha Chaudhari

I am a Python enthusiast who loves Linux and Vim. I hold a Master of Computer Science degree from NIT Trichy and have 10 years of experience in the IT industry, focusing on the Software Development Lifecycle from Requirements Gathering, Design, Development to Deployment. I have worked at IBM, Ericsson, and NetApp, and I share my knowledge on CSEstack.org.