gistfile1.py

 
def memo(f):
    """Decorator that caches the return value for each call to f(args).
    Then when called again with same args, we can just look it up."""
    cache = {}

    def _f(*args):
        try:
            return cache[args]
        except KeyError:
            cache[args] = result = f(*args)
            return result
        except TypeError:
            # some element of args can't be a dict key
            return f(*args)
    _f.cache = cache
    return _f

@memo
def best_strategy(time_remaining, wealth, income):
    if time_remaining < 6:
        # Best to just hold
        return wealth
    else:
        # Could hold or invest
        return max(best_strategy(time_remaining-6, wealth+income, income),
                   best_strategy(time_remaining-6, wealth-25+income, income+1))

print(best_strategy(210, 650, 250))    
# 9445