Gist file: https://gist.github.com/rjvitorino/d2f5f2ac53b3e86ab4883cbf8b2bec3e
Description: Cassidy's interview question of the week: a function that determines the maximum profit one can achieve by buying and selling stock once, given an array of integers representing the stock prices of a company in chronological order
from typing import List
def max_the_stock(prices: List[int]) -> int:
"""
Determine the maximum profit achievable by buying and selling a stock once.
Args:
prices (List[int]): A list of integers representing stock prices in chronological order.
Returns:
int: The maximum profit that can be achieved, or 0 if no profit is possible.
"""
if not prices:
# Edge case for empty lists
return 0
# Initialise min price to infinity and max profit to 0
min_price = float("inf")
max_profit = 0
# Update the minimum price if the current price is lower and update the maximum profit
for price in prices:
min_price = min(min_price, price)
max_profit = max(max_profit, price - min_price)
return max_profit
if __name__ == "__main__":
# Example test cases
assert max_the_stock([7, 1, 5, 3, 6, 4]) == 5 # Buy at 1, sell at 6
assert max_the_stock([7, 6, 4, 3, 1]) == 0 # No profit possible
# Additional cases
assert max_the_stock([]) == 0 # Empty list
assert max_the_stock([5]) == 0 # Single price, no transactions possible
assert max_the_stock([5, 5, 5, 5]) == 0 # No price change, no profit possible
assert max_the_stock([3, 2, 6, 1, 4]) == 4 # Buy at 2, sell at 6
assert max_the_stock([1, 2, 3, 4, 5]) == 4 # Buy at 1, sell at 5
assert max_the_stock([9, 11, 8, 5, 7, 10]) == 5 # Buy at 5, sell at 10
print("All test cases passed!")