January 30, 2002: Here's puzzle/game I call Traffic
Jam. It's modeled after the original plastic version, RushHour,
Arts. The objective is to free the target car by
moving those that are blocking it's way. Vehicles can move only
in the direction of their long axis. A simple case with the objective
of moving the red car to the exit looks like this:
||Too easy? Try this one
20, 2002: How many ways can we make change for $1 using the
six coin values ($1, 50c, 25c, 10c, 5c, 1c)? The answer is well
known, but here's a Making Change
program that will show you the solutions, plus solve a couple of
additional change making problems. Now available in Beginners and
Intermediate versions, take your choice.
January 17,2002: Sliding Coins:
The problem is to get
by sliding big/small or small/big coin pairs without changing their
Here's a minor update to the previously posted Sliding
Coins puzzle - it improves colors and the dragging of coins. Not really
very significant, just one of those "30 minute" changes
that took a week to do. Good programmers, bulldogs, and other overachievers share one characteristic - we
just don't give up.
15, 2002: T-Shirts 2 XXL just completed finding all 88 Armstrong
numbers (see below if you don't know what they are). Here's a
link to the program output page, in case you want to check
them manually. The program ran for a day and a half - surely we
could reduce that time by at least 50%....
January 14, 2002: A month or so ago we
introduced the T-Shirts 2 problem - find N digit numbers that are equal to
the sum of the Nth powers of their digits. For example, 153= 13+53+33,
Numbers with this characteristic are called Armstrong numbers or
Pluperfect Digital Invariants. In base 10, it turns out that there
are 88 of them, the largest containing 39 digits! Calculating these
numbers is non-trivial once we get over 10 digits or so - more of the kind
of stuff that PhD's get paid to play with. Here's the version
I call T-Shirts2-XXL, that will
do them all (although I haven't done it yet).
In the process I found and fixed a small error in the
"Add" operator in the Big Integers unit.
If you have previously downloaded the unit, do it again. (Or if you
download T-Shrts2 XXL source, the new version is included)
January 11, 2002: We're back! Here's
version 1 of a Doodler program which
let's you scribble on a screen area and optionally have lines
reflected at 90 or 45 degree increments.
Version 2 in the works will add additional drawing features as well as
ability to print and save images.
January 2, 2002: It looks like the
holidays are winding down - we plan a trip to Alabama this coming weekend
to help granddaughter Sarah celebrate her 8th birthday then we'll get going
on DFF projects again. Spent a
pleasant few days working with Chris (7) on his Pinewood Derby car, practicing
trumpet duets with Kaitlin (10), and working with both on the "Logical Journey of
the Zoombinis" - still one of the best games around.
They are getting better than me at solving the puzzles there though -
While browsing DFF the
other day, I ran across a note in the Scientific
Grapher program write-up that promised more information on converting
from Polar to Cartesian coordinate systems; necessary in order to display some
graphs. Today I posted this graphical demo of Polar-Cartesian
coordinate conversion over in Math-Topics.