Stockbroker

aline.py

sum(c[-1] - i if c[-1] > i else c.append(i) or 0 for c in [[0]] for i in [int(v) for v in input().split()][::-1])

bookmark.md

Stockbroker

Assume a stockbroker can predict exactly price of stock for days. How much can he make profit? If in any day he can buy one stock, sell some stocks he had, or do nothing.

code.py

sum(c[-1] - i if c[-1] > i else c.append(i) or 0                 # return profit each day.
        for c in [[0]]                                           # store day of the largest price.
            for i in [int(v) for v in input().split()][::-1])    # reversed list of price each day.

LICENSE.txt

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                    Version 2, December 2004

 Copyright (C) 2012 Nattawut Phetmak <http://about.me/neizod>

 Everyone is permitted to copy and distribute verbatim or modified
 copies of this license document, and changing it is allowed as long
 as the name is changed.

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. You just DO WHAT THE FUCK YOU WANT TO.

package.json

{
  "name": "stockbroker",

  "description": "calculate for largest profit of trading if stockbroker can predict future price.",

  "keywords": [
    "trading",
    "optimization",
    "problem"
  ]
}

test.py

profit = sum(c[-1] - i if c[-1] > i else c.append(i) or 0 for c in [[0]] for i in [int(v) for v in input().split()][::-1])

# stdin:
# 4 23 42 8 16 15

expected = 65
print("expected value: " + expected)

print("actual output: " + profit)