Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
Solved

# Help me walk through a few loops to see how many executions. I need a lesson

Posted on 2004-09-25
Medium Priority
205 Views
I'm having difficulty finding out how many executions these loops operate sum++. i'm not only interested in the answer but how youy figured it out.

A)   for(i=1 ; i<= 100 ; i++)
for (j= 1 ; j <= i; j++) sum++;

A)   i'm thinking that the first for loop goes through 100 times and the second for loop is also 100 times so 100^2 is correct?? is this right?

B) for(i = 101; i <=200; i++)
for(j= i - 1;  j <i+1;j++) sum++;

B) I tried walking through it and it seems the first loop starts out and goes through 99 times. hen thew second one is true for 99 times so 99^2
my thinking was as follows
1st time through j =100 ; 100 < 101 +1; 100++

2nd time  j=101 ; 101 <102+1; 101++
.
.
.
.
199th time j= 199 ; 199 < 200 +1 ; 200++ so stops here 199-100 = 99 times....is this the right logic??

0
Question by:tyweed420
• 3
• 2
• 2
• +1

LVL 92

Accepted Solution

objects earned 60 total points
ID: 12153143
A) No, the first loop will go 100 times, but the second loop will execute a variable number of time.
first time (i=1) it will execute once, second time (i=2) it will execute twice, etc
So total loops = 1 + 2 + 3 + ... + 100.

B) No, again right for the first loop, but not for the second.
The second loop will execute (i+1) - (i-1) times = 2 times
So total number of loops is 99 x 2 = 198 times.
0

LVL 24

Expert Comment

ID: 12153844
B) 200!

;JOOP!
0

LVL 86

Expert Comment

ID: 12153986
Classwork done then?
0

LVL 24

Expert Comment

ID: 12155171
No reason to give a wrong answer .....
;JOOP!
0

Author Comment

ID: 12156456
Objects thanks for the help you get the huge 20 points! may i ask though when you figured out part B how did you know to take (i+1) - (i-1) is that some type of formula or common knowledge proccess you used to take those two arguments and derive 2?

0

LVL 92

Expert Comment

ID: 12156544
> B) 200!

That is correct, I overlooked the <=.

> how did you know to take (i+1) - (i-1)

just the difference between the upper and lower ranges for the index.
0

Author Comment

ID: 12182959
Hey guys one last question for ya regarding counting loops. These two are very difficult for me

1)  for(int i = 100 ; i > 0  ;i--)
for(j=i;   j  <  2 * i + 2 ; j++)
sum++

1. i'm thinking the first loop goes through 99 times but then when you get into the second loop it lookslike this

i=100                 i=99           ....................      i=1
=======        ========                          =========
j=100                j=99                                         j=1
i=202                 i=20                                         i=4                                   so its 3+4+5+6..........+102 = times sum++ is executred is this correct?
102 times             101 times                                 3 times

2)           for(int i = 0 ; i <10000  ;i++)
for(j=0 ;   j *j*j < i ; j++)
sum++

this one i have no clue can someone walk me through it ?

0

LVL 24

Expert Comment

ID: 12187274
No, you won't get 2 answers for only 20 points.

;JOOP!
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

By the end of 1980s, object oriented programming using languages like C++, Simula69 and ObjectPascal gained momentum. It looked like programmers finally found the perfect language. C++ successfully combined the object oriented principles of Simula w…
In this post we will learn how to make Android Gesture Tutorial and give different functionality whenever a user Touch or Scroll android screen.
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
This tutorial will introduce the viewer to VisualVM for the Java platform application. This video explains an example program and covers the Overview, Monitor, and Heap Dump tabs.
###### Suggested Courses
Course of the Month14 days, 9 hours left to enroll