El problemo

Write some code that prints 543210012345.

You code must meet the following conditions:

• You must use single a loop (eg. for or while) and each iteration of your loop may only print one character digit.
• No if statements, no ternary operators.
• No strings, no arrays. Numbers only.
• You may only use at most one variable.
• You may use language-specific functions / methods (but it’s not necessary).

As always, use any programming language you like and post up your answers in the comments. Once there have been several attempts, I’ll post up my suggested answers. It’ll be interesting to see the different ways people do this, and the various optimization techniques that are utilized.

Good luck!

Note: When leaving a comment, indent your code blocks by four space or one tab so the formatting is saved and you don’t have to escape characters. For inline code, wrap it in backticks, eg. `This is some code`

The new iFone¹ mobile needs to be able to find and connect to the nearest phone tower. Each phone is fed a list of Cartesian coordinates of the towers within range, and a coordinate of the phone’s current position.

The coordinates and IDs of the phone towers are passed to the phone as soon as they are within range.

Write a function that takes parameters of the ID, x and y coordinates of a phone tower and if it’s closer than the current connected tower, calls the connectToTower() function passing the ID of the tower.

The phone’s coordinates are two global variables, phoneX and phoneY, while the currently connected tower has coordinates stored in cTowerX and cTowerY.

A little pseudo-code to help you along the way:

function checkTower(towerID, towerX, towerY){
    // phoneX, phoneY, cTowerX and cTowerY are available...
    find distance to currently connected tower
    find distance to passed tower
    if( passed tower is closer than currently connected tower ){
        connectToTower( towerID );
    }
}

This should be fairly straightforward. As usual, post up the answers in the comments using any programming language you like. Good luck!

Write a function that returns the height of a bouncing ball above ground in metres after specified time (in seconds) if the ball is taking five seconds to complete each bounce (up and back down) and reaches a maximum height of 3 metres at the peak of each bounce. The initial position of the ball (after 0 seconds) is at ground level (0 metres).

Your function should take as a parameter the time elapsed in seconds (t) and return a numerical value of the height of the ball after that many seconds. Any approximations should be to at least four decimal places.

Bonus points earned if your function uses only one line of code.

Hint: Think periodic / cyclic function and half your work is done. Duoble Hint: You could use Grapher.app to check your answer…

Part B

Expand your function from Part A so that every time the ball hits the ground, the boink() function is called. (Assume boink() is already defined)

Easy? I’m sure many people wouldn’t bother reading past the first sentence, but it just shows how important it is as a programmer to be familiar with math and physics, and to be able to apply your skills. Those application tasks that you hated at school were good for you.

While a lot of this could be done through using or examining readily available source code or libraries, it’s beneficial to be familiar with the basic concepts. Quoting howstuffworks, “it’s good to know”.

Continue to challenge #2