General Details

Due Date: November 29, 2018 [2018-11-29, Thursday of week 14]

The following guidelines are expected for all homework submissions:

• All homework must be typed. Homework which is not typed will be returned ungraded and will be subject to the late homework guidelines as set out on the syllabus page. PLEASE DO NOT scribble something on lined paper and rip it out of your spiral notebook — hanging chads went out with the presidential election in 2000.
• I don't care too much about what font you use or how large your margins are; however, you might want to check out a monospaced font for typing code, as it will be easy to see the indentations.
• Speaking of indenting, PLEASE DON'T USE TABS TO INDENT YOUR CODE. Tabs can often get interpreted differently by different computers and applications, and could make code that is nicely formatted on your computer look "all over the map" on my computer or printer. USE SPACES INSTEAD. You can set up almost every modern text editor to insert spaces whenever you press the TAB key, or you can simply pound the spacebar.
• Work with a partner. This mimics an industry code development model called "pair programming" which is part of the Extreme Programming software development method. Feel free to collaborate in your pairs as much as you want, preferably doing the entire assignment together.
• DO NOT share your work between groups. Doing so will count as plagiarism. If you wish to discuss solutions with another group over coffee in the Lair, that's fine as long as it is kept at the conceptual level, but each group needs to turn in its own version of the solutions.
• You only need to turn in one copy per group.
• If you'd like to use the jsfiddle website to do your programs, that is great. Simply save the program in jsfiddle as a shared fiddle, then copy and embed a link to the fiddle into your homework where the answer goes for that problem. I'll use the link to go to YOUR fiddle and run the code. To save your fiddles you'll need to sign up for an account…

Problems From Chapter 4

Ch 4, #22: Explain, in your own words, as precisely as possiblethe behavior of this script:

      var i = 0;
      while( i < 10 ) {
         continue;
         i += 1;
      }
      alert( "All done" );
                

Ch 4, #26: One way to "speed up" the prime number-testing script is as follows:

• If n is divisible by 2, you know immediately that n is composite
• Otherwise, test the divisors 3, 5, 7, 9, 11, …, to the square root of n

Why does this work? Rewrite the script to use this improved algorithm.

pg 126, #1 : Write a for statement that alerts 10, then alerts 9, and so on, until a final alert of 0.

pg 126, #2 : Write a little script that computes the value of the product of the integers 1 through 20 (inclusive). Use a for statement.

pg 126, #3 : What would happen if, in Figure 4.6, the value of the last object's next property were not null but rather a reference to the first object in the chain?

pg 126, #4 : In the multiplication table script, the inner loop uses the variable j to iterate through the columns. What would the script have produced if the programmer had accidentally used the variable i for both the outer and inner loop indices? [Hint: be careful about array bounds.]

Problems From Chapter 5

Ch 5, #3 : Write a function that returns the average of all of the items in an array. For example, average( [4, 5, 7, 2] ) should return 4.5.

Ch 5, #5 : Write a function that accepts two numbers and returns a random number between the two values.

Ch 5, #8 : Write a function that returns the number of occurrences of a given character in a string. For example, given the string "Rat-a-tat-tat" and the character "t", your function should return 5.

Ch 5, #10: Use the Wolfram Alpha decision engine (http://www.wolframalpha.com/) to determine why the original balanceAfter function from this chapter gives troublesome results for negative numbers of compounding periods. Ask Wolfram Alpha to graph the function 1000 * (1 + 0.05/n)10n and explain what you are seeing for negative values of n.

Ch 5, #11: What is produced by the sum function from this chapter when given an argument that is not an array? Is this worrisome? Discuss whether or not the function should be rewritten to check for a non-array argument.

Ch 5, #15: Test the isPrime function in a shell on the following arguments: undefined, null, false, true, "4", " 2 ", " 2 ", and [19].

Problems From Chapter 6

Ch 6, #25: Create a web page with at least three levels of nested elements, such that its overall structure looks like this:

      <div>
         <div>
            <div>
            </div>
         </div>
      </div>
                

Give each element a click handler that identifies, through an alert dialog, the clicked-on element and whether or not the event is in the capturing or bubbling phase. Open the web page and, before clicking on various elements, predict the sequence of alert messages that you will see. Open the same page and click around using different web browsers as well, and determine which browsers have similar or different event behavior. [Hint: read carefully the section in your text book about bubbling and capturing so you understand what is being asked of your program.]

pg 206, #3 : Draw a complete tree diagram for the temperature converter web page in Section 6.1.2.

Implementation Exercises

These programming problems are designed to give you practice at creating algorithmic solutions to some straightforward problems. The intent is not to overload you with tons of homework; rather, it is to help you practice the concepts you have learned in class about breaking the problem down into parts, figuring out the algorithm for each part, writing the whole thing down, doing a desk check, and coding it up and testing it with various inputs. To that end, You may select any two of these three problems. If you would like to do all three, feel free to do so, of course. I'll give you one extra credit point for your correct solution.

Exercise 1: Expand the tic-tac-toe game from your text book to do a four-by-four game instead of three-by-three. (Note: this sounds a lot harder than it is...) The code begins on page 254 of your book.

Exercise 2 [part one of two parts]:Ch 7, #22: Write a function that takes in a string and returns the reversal of the string. For example:

      reversal( "" )          // returns ""  (the empty string)
      reversal( "a" )         // returns "a"
      reversal( "string" )    // returns "gnirts"
            

Exercise 2 [part two of two parts]Ch 7, #23: Next, build a web interface to the string reversal function. Your web page should have a single input box and a button labeled Reverse. Clicking the button should cause the text in the input box to be replaced with the reverse of its current contents. (Bonus: see how few lines of code you can use to accomplish this task.)

Exercise 3: Given a total monetary amount and set of coin denominations, determine the smallest number of coins required to make the total amount. For example, given the total amount of $1.23 and the denominations 50, 25, 10, 5, and 1, the answer should be two-50, two-10 and three-one coins. If some denomination is provided which is unusable, such as a negative value, the program should simply say "IMPOSSIBLE" for that denomination. The program should be contained in a web page, in which the user inputs an arbitrary amount of money (expressed as a non-negative, whole number of cents) in one text box, followed by a sequence of coin denominations (distinct positive integers) in the second text box. The page must then display in its footer area the optimal way of making change for the given amount using the given set of denominations. If there is no way to make the change, the program must output the message IMPOSSIBLE.

Python Programming Problems

The following problems are from the book "Python for Everyone" by Cay Horstmann and Rance D. Necaise, ISBN 978-1-118-62613-9.

Exercise 4: (PYTHON PROGRAMMING — text exsample 3.2, page 131) Two circles may intersect at a single point, at two points, or at an unlimited number of points when the two circles are coincident (on top of each other). If the circles do NOT intersect, one circle may be contained entirely within the other, or they may be completely separate. Your task is to write a program in Python that obtains the parameters for two circles and reports whether they intersect. For each circle, the inputs should be the X and Y coordinate (on a Cartesian grid) of the center, and the radius of the circle. The output should be one and only one of the possible configurations listed above, as well as the distance between the two center points. (Hint: the distance can be determined by using the Pythagorean Theorem.)

Exercise 5: (PYTHON PROGRAMMING — Business P3.35) Calculating the tip when you go to a restaurant is not difficult, but your restaurant wants to suggest a tip according to the service diners receive. Write a program in Python that calculates a tip according to the diner's satisfaction as follows:

• Ask for the diner's satisfaction level using values 1 (satisfied) to 3 (dissatisfied)
• If the diner is totally satisfied (value 1), calculate a 20 percent tip
• If the diner is satisfied (value 2), calculate a 15 percent tip
• If the diner is totally dissatisfied (value 3), calculate a 10 percent tip
• Report the satisfaction level, in words, and the tip, in dollars and cents

Exercise 6: (PYTHON PROGRAMMING — Science P3.40) Sound level L in units of decibel (dB) is calculated by
L = 20 log( p / p₀ ) where p is the sound pressure of the sound and p₀ is a reference pressure of 2 * 10^-6. The p values are given in "Pascals", abbreviated by "Pa". The following table gives some sample descriptions of certain sound levels:

1	Threshold of pain	130 dB
2	Possible hearing damamge	120 dB
3	Jackhammer at 1 meter distance	100 dB
4	Traffic on a busy roadway at 10 meters distance	90 dB
5	Normal conversation	60 dB
6	Calm library	30 dB
7	Light leaf rustling sound	0 dB

Write a Python program that reads a value and a unit, either dB or Pa, and then prints the closest description from the table above.

Exercise 7: (PYTHON PROGRAMMING — Science P3.44) A mass, m of 2 kilograms is attached to the end of a rope of length
r = 3 meters. The mass is whirled around at high speed. The rope can withstand a maximum tension T of 60 Newtons before it will snap. Write a program that accepts a rotation speed V and determines whether such a speed will cause the rope to break. Use the formula T = mV² / r to calculate.