Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

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

Posted on 2004-09-25
8
Medium Priority
?
204 Views
Last Modified: 2010-03-31
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
Comment
Question by:tyweed420
  • 3
  • 2
  • 2
  • +1
8 Comments
 
LVL 92

Accepted Solution

by:
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

by:sciuriware
ID: 12153844
B) 200!

;JOOP!
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12153986
Classwork done then?
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 24

Expert Comment

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

Author Comment

by:tyweed420
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?

Thanks in advance!
0
 
LVL 92

Expert Comment

by:objects
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

by:tyweed420
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

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

;JOOP!
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

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

Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
In this post we will learn how to make Android Gesture Tutorial and give different functionality whenever a user Touch or Scroll android screen.
Video by: Michael
Viewers learn about how to reduce the potential repetitiveness of coding in main by developing methods to perform specific tasks for their program. Additionally, objects are introduced for the purpose of learning how to call methods in Java. Define …
This tutorial covers a practical example of lazy loading technique and early loading technique in a Singleton Design Pattern.
Suggested Courses

971 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question