Programming Puzzle 1 - Simple Loop

[Tom Cone Jr]

If you've been thinking that this summer might be a good time to learn a little xbasic, I have a treat in store for you.

I'm planning to post a series of programming puzzles for you to work on. Puzzles that must be worked out using xbasic.

Hopefully, these puzzles will give us a springboard from which we can discuss, teach, learn, and benefit from each other's experience.

In any event, here's my first offering.

The solution should be presented in the form of an xbasic script. The script should be posted here, or attached to a reply here. You should expect comments, questions, and even corrections. The object is not to "show off" but to provide a safe, non-judgmental area, where people who may be curious about programming, especially, programming in xbasic, can play, have fun, and learn. I rather suspect we'll see more than one way to solve these things. Alpha Five is nothing if not flexible, right?

Hope you like it.

-- tom

[CALocklin]

OK, here's a down and dirty solution: (I just hope I got the right answer!)

OPTION strict
'Variables should not be "one word" or "one letter". Not because they won't 
'work but because they can make debugging harder in long scripts.
'This is an "abbreviated two word" variable - two words to help make it 
'unique for search purposes and abbreviated to make it faster to type. 
'even_sum ==> esum.
DIM esum as N
'A single letter preceeded by "q" is easier to find in a search than, in this 
'case, just the letter "e". The letter "e" is used 18 times but "qe" only 3.
DIM qe as N
'Set initial value to 0.
esum = 0
'Many people forget that a FOR...NEXT statement can also use a STEP command.
FOR qe = 102 to 302 step 2
	esum = esum + qe
NEXT
DIM msg as C
'Although it's possible to use ui_msg_box( "TOTAL", "" + esum ) and let A5 do the 
'conversion from number to text, it's valuable to know that it's actually faster 
'if you explicitly specify the conversion. The extra time isn't noticeable in this 
'case but it can be noticeable when a calculation is being done inside a long loop.
msg = "The sum of the even numbers between 101 and 302 is:  " + ltrim( str( esum ) )
ui_msg_box( "TOTAL", msg, ui_information_symbol )

By the way, "Option Strict" requires that all variables be DIMmed. While it does have its advantages, I personally find it too annoying and virtually never use it. But that does require some care when naming variables to make sure you don't accidentally try to use a "local" variable that is already defined as global or shared.

[BigBoss1]

Hi
Just a small addition to CALockin's answer to include the iterations in the loop.

[DaveM]

David and Cal,

If you use the 101 instead of the 102, your answer is actually less. which is correct? Tom said 101-302.

[CALocklin]

Dave, I'm happy to say you don't read any better than I do!

I completely missed the part where Tom said, "and the number of times your code iterated through your loop."

You missed the part where he said, "sums the even numbered values". 101 wasn't even last time I checked.

[Tom Cone Jr]

Yes, grasshoppers. Understanding the question is the key to enlightenment.

For the beginners who may be lurking nearby, would anyone like to explain how the "For ... Next" loop does it's magic?

So far no one has attempted a solution using a "While ... End While" loop. Any takers?

[Mbuso]

Heres a different approach...

will work with any two numbers from 0 to ... [tested with 1000000]

enjoy :-)

[Stan Mathews]

A while loop version. Some lesser used functions and methods employed.

option strict
'If you place the OPTION STRICT command at the top of a script then you must declare variables explicitly using the DIM command.
dim entries_to_use as C = ""
dim qx as N = 101
dim loops as N = 0
'Dimming all variables in one place can make them easier to locate
TRACE.CLEAR() 'Clear the Trace window before writing text to it.
WHILE qx < 303
	IF mod(qx,2) = 0 'checks for even number
		entries_to_use = entries_to_use+alltrim(str(qx))+crlf() 'builds crlf() delimited string
		traceln("Even number "+alltrim(str(qx))+" current loop value "+alltrim(str(loops))) 'writes the number and current loop to the trace window
	END IF
	qx = qx + 1 'increments possible values to be summed variable
	loops = increment_value(loops) 'increments loop variable
END WHILE

qx = *total(entries_to_use) 'The *TOTAL() function totals a list of numeric entries.
'Note that there is nothing illegal about re-using a numeric variable for a second purpose
traceln("Sum "+alltrim(str(qx))+" total loops "+alltrim(str(loops)))
ui_msg_box("Note","Activate the Error tab of the next window to appear."+crlf()+"to see the sum of values and loop total.")
A5_TOGGLE_TRACE_WINDOW() 'The A5_TOGGLE_TRACE_WINDOW() function opens the Trace window if it is closed, and closes it if it is open.

Took some liberties with "and then display the answer in a message box....".

[Al Buchholz]

Took some liberties with "and then display the answer in a message box....".

Your shore liberty is canceled - again

[Stan Mathews]

Another take using xdialog to display the results.

option strict
'If you place the OPTION STRICT command at the top of a script then you must declare variables explicitly using the DIM command.
dim entries_to_use as C = ""
dim qx as N = 101
dim loops as N = 0
DIM SHARED varC_result as C
dim ok_button_label as C = "&OK"
'Dimming all variables in one place can make them easier to locate
FOR qx = if(mod(qx,2)=0,qx,qx+1) TO 302 step 2 'computed starting loop value, optional step parameter
	entries_to_use = entries_to_use+alltrim(str(qx))+crlf()
	loops = increment_value(loops)
NEXT qx
qx = *total(entries_to_use) 'The *TOTAL() function totals a list of numeric entries.
'xdialog follows to display values, The R directive makes the text in a Text Box read-only.
varC_result = ui_dlg_box("Alpha Five",<<%dlg%
{region}
Loops:| [%r%.40loops];
Sum of Values:| [%r%.40qx];
{endregion};
{line=1,0};
{region}
<*15=ok_button_label!OK>
{endregion};
%dlg%)

[GGandhi]

puzzle conditions:
1> use option strict
2> add up even numbers between 101 and 302 both inclusive
3> show the number of iterations and the result in a message box
4> include comments.
while i am not certainly an expert this is my attempt...

option strict
'dim all variables 
'x iteration variable, j number palce holder for start and end
'sumx total of even nunbers
'msg 
dim x as n=0
dim j as n
dim sumx as n=0
dim msg as c=""
for j=101 to 302
	x=x+1
	if mod(j,2)=0
		sumx=sumx+j
		end if
	next
	msg=("Total iterations:  "+x+" Total of the even numbers:  "+sumx)
	ui_msg_box("Total Iterations",x)
	ui_msg_box("Total of the even numbers",sumx)
	ui_msg_box("Puzzle",msg)

[Tom Cone Jr]

Govindan, that's very good. You've used the loop correctly. Notice several things:

a) the message board reformatted your code, forcing every line to be left justified. You can overcome this and preserve the formatting in your script if you use the "advanced" message board editor (choose "Go Advanced" button). Then select the text to be "preserved" and apply "CODE" tags to it. If this isn't clear let us know.

b) In these lines:

msg=("Total iterations: "+x+" Total of the even numbers: "+sumx)
ui_msg_box("Total Iterations",x)
ui_msg_box("Total of the even numbers",sumx)

you're concatenating character strings with numeric values. To do this Alpha must convert your numeric values to character strings for you. While Alpha tries hard to do this "implied" data type conversion when it's needed, it does not always succeed. A better practice is to explicitly convert your numeric data to character strings before doing the concatenation. Check Cal Locklin's sample code in this thread (above).

c) Also, notice that once the first "even" number is encountered, you could optimize the code by stepping through the number range two numbers at a time. Bouncing from even to even so to speak. This would cut the number of trips through loop in half if you see what I mean.

Good work.

-- tom

[CALocklin]

...
'Dimming all variables in one place can make them easier to locate
...

And alphabetizing a long list makes it easier also. I do this often enough that I've included a "sort clipboard" routine in my AIMS Grab Bag. (At least I think it's there. I know it's in my personal version.) The code is really simple - just one line - and could be added to a custom "Sort Clipboard" button on your Code Editor toolbar:

clipboard.set_data( sortsubstr( clipboard.get_data(), crlf() ) )

To use it for sorting a group of lines in your Code Editor, just highlight the lines, press Ctrl-C to copy them, click the custom button to sort them, and press Ctrl-V to replace the already selected "old" list with the sorted string. (Ctrl-V is the shortcut key for "Paste".)

I also use this in other places. For example, I've sometimes created a crlf list for the user to select from, added and/or deleted from it, and then want to sort the list to make it easier for the user to work with.

[GGandhi]

Govindan, that's very good. You've used the loop correctly. Notice several things:

a) the message board reformatted your code, forcing every line to be left justified. You can overcome this and preserve the formatting in your script if you use the "advanced" message board editor (choose "Go Advanced" button). Then select the text to be "preserved" and apply "CODE" tags to it. If this isn't clear let us know.

b) In these lines:

msg=("Total iterations: "+x+" Total of the even numbers: "+sumx)
ui_msg_box("Total Iterations",x)
ui_msg_box("Total of the even numbers",sumx)

you're concatenating character strings with numeric values. To do this Alpha must convert your numeric values to character strings for you. While Alpha tries hard to do this "implied" data type conversion when it's needed, it does not always succeed. A better practice is to explicitly convert your numeric data to character strings before doing the concatenation. Check Cal Locklin's sample code in this thread (above).

c) Also, notice that once the first "even" number is encountered, you could optimize the code by stepping through the number range two numbers at a time. Bouncing from even to even so to speak. This would cut the number of trips through loop in half if you see what I mean.

Good work.

-- tom

Thank you, Much appreciated.

gandhi

[pmanandhar]

This is the basic, simplest and best problem for anyone learning to program. I saw some of the simplest code and a little challenging ones. I was wondering if anyone even thought to solve this without using a loop?? Anyone?? I am sorry that I'm not following the question to solve the answer but my point is to view things little differently.

Check this out:
Below is the code to add even/odd numbers between n1 and n2 without using any loops. I'm sorry again that I'm violating the rules of the question and not following instructions. But here is something I got.. I created a formula to add odd and even numbers.

        dim n1 as n 
	dim n2 as n 
	dim x1 as n 
	dim x2 as n 
	dim add_even as n = 0
	dim add_odd as n = 0
	dim msg as c=""
	n1 = 101
	n2 = 302
	x1 = n1
	x2 = n2
	if (mod(n1,2)=0)
	   n1=n1-1
	end if
	if (mod(n2,2)=1)
	   n2=n2-1
	end if
	if (mod(x1,2)=0)
	   x1=x1+1
	end if
	if (mod(x2,2)=1)
	   x2=x2+1
	end if
	add_even=((n2^2)-(n1^2)+(n2*2)+1)/4
	add_odd =((x2^2)-(x1^2)+(x1*2)-1)/4
	?add_even+"<br/>"
	?add_odd+""

[Tom Cone Jr]

Thinking outside the box, are we, now?

Pratik, your solution gets the correct result. However, our fearless scorekeeper, "Ignatious A. Pickypicky", has deducted points for (a) the absence of explanatory comments; and (b) the failure to display the computed results in a message box. Care to try again? Maybe you'll catch Pickypicky in a better mood!

[pmanandhar]

hi tom,
I wasn't really worried about the points but now you said it so I made some changes with comments, loop and message box. So, do I get the bonus point for the least iterations.

option strict
	'dim all variables 
	'n1 = starting value , n2 = ending value (both inclusive) 
	dim n1 as n = 0                  
	dim n2 as n = 0
	dim x1 as n = 0
	dim x2 as n = 0
	dim i as n = 0
	dim add_even as n = 0	' to add even numbers
	dim add_odd as n = 0	' to add odd number (optional)
	dim msg as c=""
	n1 = 101			' start value to add
	n2 = 302			' end value to stop adding
	x1 = n1
	x2 = n2
	i = 1
	if (mod(n1,2)=0)	' check if even
	   n1=n1-1			'subtract one because by formula works with starting value as odd and ending as even
	end if
	if (mod(n2,2)=1)	' similiar to above reason
	   n2=n2-1
	end if
	if (mod(x1,2)=0)
	   x1=x1+1
	end if
	if (mod(x2,2)=1)
	   x2=x2+1
	end if
	for i = 1 to 1
		add_even=((n2^2)-(n1^2)+(n2*2)+1)/4 'formula to add even values between n1 and n2
		add_odd =((x2^2)-(x1^2)+(x1*2)-1)/4 'formula to add odd values between n1 and n2
	next 
	ui_msg_box("Total Iterations",i)
	ui_msg_box("Total of the even numbers",add_even)
	ui_msg_box("Total of the odd numbers",add_odd)

[Tom Cone Jr]

So, do I get the bonus point for the least iterations?

Sorry, no. By stepping out of the bounds created for the exercse you've earned the careful attention of our venerable scorekeeper, Prof. Pickypicky. He will be keeping a sharp eye on your future puzzle submittals!

ps. I'd be tempted to ask him to reconsider if your script furnished a "proof" for the even number formula you employed.

-- tom

[pmanandhar]

hey tom,
I am new to this forum and don't know what you and your "Prof. Pickypicky" is talking about. Maybe I'm little careless that even in my classes I rarely got an A (instead A- or B+) even though I get the job done. I don't know what proof are you asking and i don't know how to proof ?? I am good in math so I just took some time and came up with this formula. Now if you are interested as how I came up with this formula then I can explain but still its little complicated to explain. you can try using different values in n1 and n2 several times. That works so is that considered "proof"??

[Tom Cone Jr]

Pratik,

I was mostly pulling your leg. Trying to be facetious. No mathematical proof is necessary. Thanks for contributing to this thread. I look forward to your answers on other puzzles in the future. -- tom

[CALocklin]

Nice job Pratik! When I posted my original solution I was pretty sure there had to be some way to do it without any iterations but didn't have the time to work it out. And seeing your solution - probably not the ability either.

[Mbuso]

upon a realisation that my input attracts no response other than anonymous respondents through email and private messages. No harm in posting another version, yet in attempt to contribution in a speedier progress for a would be alpha fellow.

regards,

[Tom Cone Jr]

Mbuso,

Very nice! Thinking outside the box. Your solution does not use a loop, but is ingenious nevertheless. In your algorithm you adjust the end points of the number range, then compute both the number of "even" terms and the avg over the entire range. Multiplying them together you get the sum. Very clever, grasshopper! Prof. Pickypicky will be watching you closely, too!

[Mbuso]

...Very clever, grasshopper!...

*blushing* ...

with a slight modification the same can be applied to calculate sum of equal contributions made in to investment or loan repayment. Which indeed, can also be done the snaky route (loop:-)

[pmanandhar]

CALocklin - Its not that difficult and you definitely have the ability (maybe not time). It took me a while to figure out the logic and formula. I saw Mbuso's logic too and its way easier than the way I was doing. His logic was to get the start and end numbers to be even. Then, get the average (easy to calculate), and times no. of even numbers which is (N+1)/2.. That's it.. brilliant..
I was also thinking similiar but the question wanted to calcuate from 101 -302. So wanted the input to be starting -odd and ending- even numbers. I did it for adding odd numbers which made little complications.

[Mbuso]

thanx pmanandhar.
interesting to read your work since you have a taste for math, and background in cpp, as seen in flyPuzzle :-)

[jeb richardson]

OPTION strict
dim sum as N
'defining sum variable as Number. Sum will be used to get the total sum of the even number through the range.
dim qx as N
'defining qx variable as Number. QX will be used as the loop.
dim lnum as N
'defining lnum variable as Number. Lnum will be used to get the total times the loop was done.
sum=0
lnum=0
FOR qx = 102 TO 302 step 2
	'starting the loop. Stating loop is is going to be ran from 102 to 302. 'Step 2' defines the number to increase by after each loop.
	sum=sum+qx
	'equation that gets the value for each loop cycle(each QX) and eventually will add them together.
	lnum=lnum+1
	'equation that sets the first loop to 1. The second loop to 2. The third loop to 3, etc.
next
'goes to next part of loop(next QX).
message="The sum of the even numbers through the range 102-302 is: "+sum
message2="The number of times the code was iterated through the loop was: "+lnum
ui_msg_box("Jeb's Calculation",message +crlf()+message2)

[Tom Cone Jr]

Jeb, good try. Prof. Ignatious Pickypicky has several comments for your elucidation (his word, not mine!)

1) The pound symbol on the "Next" line throws an error. It doesn't belong.

2) The message box fails to display because the variables "message" and "message2" haven't been declared,
and OPTION STRICT is on.

3) The professor's eyes aren't what they used to be. Consider formatting your scripts so they're easier
to read. (Example below to give you some ideas).

4) It's not necessary to comment every line. Some things will always be obvious when you come back to
the script years later. Others will not. The latter is what must be documented / commented.

5) It's customary to indent lines inside a code block / loop structure.

OPTION strict		

'recommend DIMing all vars at the top
dim sum as N		'defining sum variable as Number. Sum will be used to get the 
			'total sum of the even number through the range.
dim qx as N		'defining qx variable as Number. QX will be used as the loop.
dim lnum as N		'defining lnum variable as Number. Lnum will be used to get the 
			'total times the loop was done.
dim qx as N		'loop counter (index)
dim message as C 	'text string for message box
dim message2 as C	'ditto


sum=0		'giving the sum variable a value of zero.
lnum=0		'giving the lnum variable a value of zero.

for qx = 102 to 302 step 2	'starting the loop. Stating loop is is going to be 
				'ran from 102 to 302. 'Step 2' defines the number 
				'to increase by after each loop.

	sum=sum+qx	'equation that gets the value for each loop cycle(each QX) and 
			'eventually will add them together.

	lnum=lnum+1	'equation that sets the first loop to 1. The second loop to 2. 
			'The third loop to 3, etc.

next	'goes to next part of loop(next QX).

dim message as C
dim message2 as C

'assigning the total sum message for the pop up message.
message="The sum of the even numbers through the range 102-302 is: "+ltrim(str(sum))

'assigning the total lnum or total times the loop was done, for the pop up message.
message2="The number of times the code was iterated through the loop was: "+ltrim(str(lnum))

ui_msg_box("Jeb's Calculation",message +crlf()+message2)	'message box that gives 
					'the results of the calculation. LNUM and SUM

.

[The Mage]

OPTION strict

dim first as N		'Starting number
dim last as N		'Ending number
dim total as N		'For final total
dim count as N		'To count the number of times this code is run, but it won't be that important as you will see.

count = 0		'Starting counter at 0

first = 102		'Starting point
last = 302		'Ending point

total = ( ( first + last ) * ( last - first ) ) / 4
			'By adding in the first and last numbers I am figuring out a standard number for the math
			'and by subtracting the last and first from eachother, I am counting the total of the 
			'numbers between the first and last.  Since I am adding in both first and last numbers,
			'I only need to figure in half of those numbers, and since only even numbers are counted,
			'I need only half of those numbers still.  So I divide the total by 4.  
			'logically it should have divided the (last-first) before being multiplied, but the result is the same.

count = count + 1	'Adding to the counter

			'Results:
ui_msg_box( " Total" , total ,UI_ATTENTION_SYMBOL )	

			'Number of times the formula had to be run:
ui_msg_box( "Times Run" , count , UI_ATTENTION_SYMBOL )

Admittedly I am cheating here by not using a loop.

[Tom Reese]

As I am very new to xbasic my version to puzzle 1 is simple, but I believe it gets the job done.
Would appreciate any comments that may be needed or helpful.

Now to see if I can find Puzzle 2.

'Date Created: 09-Nov-2011 05:23:03 PM
'Last Updated: 10-Nov-2011 08:12:35 AM
'Created By : T. E. Reese
'Updated By : T. E. Reese
option strict

dim target_num as n = 0 'used to determine if number is even
dim i as n = 0
dim result as n = 0 'result adds the total of the even numbers
dim num_loops as n = 0 'counts the number of interations

for i = 302 to 101 step-2
num_loops = num_loops + 1
target_num = i
if mod(target_num,2)= 0 then
result=result+target_num
end if
next i

ui_msg_box("Program Puzzle One","The answeres are Sum = "+ alltrim(str(result))+" Loops = "+alltrim(str(num_loops)))

end