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  #1  
Old 06-13-2008, 09:46 PM
Tolnaftate2004 Tolnaftate2004 is offline
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Programming Exercise #4: Super fun edition

Today's challenge will include 2 problems:
  1. hard Suppose that you are organizing housing accommodations for a group of four hundred university students. Space is limited and only one hundred of the students will receive places in the dormitory. To complicate matters, the Dean has provided you with a list of pairs of incompatible students, and requested that no pair from this list appear in your final choice.
    The point of this exercise is to GENERATE DISCUSSION. We are not asking you to WRITE the code, merely speculate as to how you might do it. BUT IF YOU FEEL COMPELLED, write the code to accomodate arbitrary lists from the Dean.
  2. easy Solve this problem.

Note From Hell Raven: the 100 students are rooming in pairs of 2. So that is 50 pairs (I do not believe this was clear...)
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Killa Be: when i got that locker in 6th grade the only thing in it was a picture of a midget useing a firehose :/

Last edited by Kristi; 06-16-2008 at 07:29 PM..
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  #2  
Old 06-14-2008, 12:47 AM
DrakilorP2P DrakilorP2P is offline
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Only primes are incompatible to other numbers? There's only 61 primes below 400. Isn't this easily solvable by including everyone who isn't a prime until you run out of space?
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  #3  
Old 06-14-2008, 01:10 AM
cbk1994 cbk1994 is offline
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Quote:
Originally Posted by DrakilorP2P View Post
Only primes are incompatible to other numbers? There's only 61 primes below 400. Isn't this easily solvable by including everyone who isn't a prime until you run out of space?
I guess the problem is figuring out who is a prime and who isn't ... but if I recall that's quite easy.
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Old 06-14-2008, 03:01 AM
DrakilorP2P DrakilorP2P is offline
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Quote:
Originally Posted by cbk1994 View Post
I guess the problem is figuring out who is a prime and who isn't ... but if I recall that's quite easy.
It's basic level programming.
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Old 06-14-2008, 03:15 AM
Tolnaftate2004 Tolnaftate2004 is offline
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It doesn't matter who is included. Make it include only 100 people, I don't care... Finding primes is trivial. I'm sure I could go online and find a list of them, this is not the point of the exercise.

I have done this for you:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397
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Killa Be: when i got that locker in 6th grade the only thing in it was a picture of a midget useing a firehose :/
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  #6  
Old 06-14-2008, 04:25 AM
cbk1994 cbk1994 is offline
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Quote:
Originally Posted by Tolnaftate2004 View Post
It doesn't matter who is included. Make it include only 100 people, I don't care... Finding primes is trivial. I'm sure I could go online and find a list of them, this is not the point of the exercise.

I have done this for you:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397
Easiest way has GOT to be to loop through every possible combination of two numbers that could possibly be a prime. Most efficient, too!
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Old 06-14-2008, 04:39 AM
Tolnaftate2004 Tolnaftate2004 is offline
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Quote:
Originally Posted by cbk1994 View Post
Easiest way has GOT to be to loop through every possible combination of two numbers that could possibly be a prime. Most efficient, too!
I updated the exercise. So, primes are no longer involved.
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Old 06-14-2008, 04:53 AM
cbk1994 cbk1994 is offline
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PHP Code:
function onCreated()
{
  
temp.start timevar2;
  
  
temp.incompatible = {
                        { 
1},
                        { 
3},
                        { 
5},
                        { 
6}
                      };
  
  
temp.chosen null;
  
temp.sets null;
  
  for ( 
temp.0100++ )
  {
    
temp.moveOn false;
    
    while ( ! 
moveOn )
    {
      
temp.person1 intrandom0400 ) );
      
temp.person2 intrandom0400 ) );
      
      if ( 
chosen.index( @ person1 ) != -|| chosen.index( @ person2 ) != -|| person1 == person2 )
      {
        continue;
      }
      
      for ( 
temp.incompatible )
      {
        if ( ( 
a[0] == person1 && a[1] == person2 ) || ( a[0] == person2 || a[1] == person1 ) )
        {
          
// Incompatible
          
continue;
        }
      }
      
      
chosen.addperson1 );
      
chosen.addperson2 );
      
      
sets.add( { person1person2 } );
      
      
moveOn true;
    }
  }
  
  for ( 
temp.set sets )
  {
    echo( 
"Set:" SPC set[0SPC "and" SPC set[1] );
  }
  
  echo( 
"Time taken:" SPC timevar2 start SPC "seconds." );

I made it as inefficient as possible. It's rather fun to make inefficient code .
I don't know why.

PHP Code:
Set59 and 119
Set
166 and 136
Set
279 and 156
Set
131 and 142
Set
195 and 397
Set
364 and 340
Set
314 and 382
Set
326 and 216
Set
352 and 140
Set
366 and 139
Set
12 and 32
Set
104 and 21
Set
92 and 75
Set
307 and 68
Set
271 and 367
Set
187 and 38
Set
103 and 66
Set
194 and 235
Set
209 and 390
Set
232 and 174
Set
331 and 147
Set
363 and 109
Set
398 and 329
Set
249 and 11
Set
362 and 354
Set
29 and 312
Set
170 and 337
Set
380 and 42
Set
304 and 167
Set
80 and 8
Set
234 and 275
Set
244 and 44
Set
265 and 76
Set
218 and 197
Set
224 and 375
Set
55 and 188
Set
84 and 54
Set
118 and 334
Set
288 and 98
Set
135 and 318
Set
10 and 305
Set
347 and 160
Set
158 and 28
Set
169 and 393
Set
303 and 13
Set
90 and 255
Set
230 and 22
Set
302 and 138
Set
240 and 37
Set
57 and 251
Set
343 and 313
Set
242 and 291
Set
73 and 0
Set
319 and 243
Set
394 and 223
Set
256 and 31
Set
392 and 346
Set
287 and 359
Set
261 and 117
Set
33 and 58
Set
186 and 283
Set
201 and 88
Set
126 and 78
Set
293 and 69
Set
360 and 65
Set
309 and 130
Set
162 and 95
Set
112 and 49
Set
339 and 200
Set
214 and 106
Set
184 and 231
Set
47 and 105
Set
15 and 237
Set
133 and 282
Set
205 and 72
Set
207 and 61
Set
146 and 125
Set
381 and 257
Set
64 and 149
Set
128 and 268
Set
324 and 322
Set
and 122
Set
226 and 46
Set
306 and 51
Set
178 and 35
Set
248 and 185
Set
369 and 155
Set
43 and 145
Set
183 and 311
Set
91 and 353
Set
14 and 115
Set
157 and 358
Set
213 and 171
Set
289 and 350
Set
290 and 286
Set
87 and 388
Set
217 and 159
Set
294 and 357
Set
148 and 24
Set
374 and 1
Time taken
0.008700847 seconds
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  #9  
Old 06-14-2008, 05:11 AM
Tolnaftate2004 Tolnaftate2004 is offline
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I tried your code and it failed to perform the task. Leaving this to chance is probably a bad idea, seeing as it could lead to an infinite loop.
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Old 06-14-2008, 05:15 AM
cbk1994 cbk1994 is offline
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Quote:
Originally Posted by Tolnaftate2004 View Post
I tried your code and it failed to perform the task. Leaving this to chance is probably a bad idea, seeing as it could lead to an infinite loop.
Worked fine for me ;o

The whole goal was inefficiency
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Old 06-14-2008, 05:57 AM
Tolnaftate2004 Tolnaftate2004 is offline
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Quote:
Originally Posted by cbk1994 View Post
Worked fine for me ;o

The whole goal was inefficiency
Well I changed the incompatibilities so that any person would only match up with one other person.
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Old 06-14-2008, 06:12 AM
cbk1994 cbk1994 is offline
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Quote:
Originally Posted by Tolnaftate2004 View Post
Well I changed the incompatibilities so that any person would only match up with one other person.
o

Probably hit a max loop limit.
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Old 06-14-2008, 07:26 AM
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I suppose what you would have to do is this:

Starting with 400 students, loop through and select 100 students at random.
Then go through those 100 students and group then until you have 50 groups.
If you have 2 students who are together on the incompatibility list, flip them with another set at random, as described below:

1 & 2
v
^
3 & 4

3 & 2
1 & 4

If any of those 2 are on the incompatibility list, then repeat the process. Once everything is OK, then you've got your list.

Here's the script I made to accompany this concept:

PHP Code:
function onCreated()
{
  
this.start timevar2;
  
  
this.incompatability = {
    {
102284},
    {
392126},
    {
12},
    {
34},
    {
56},
    {
78}
  };
  
  
  
this.studentsSelected.clear();
  
this.studentGroups.clear();
  
  
numStudentsSelected 0;
  
// Select students at random
  
for (0100i++)
  {
    
int(random(0400));
    
    if (
this.studentsSelected.index(f) == -1)
    {
      
this.studentsSelected.add(f);
    } else
    {
      
i--; continue;
    }
  }
  
  
// Group them
  
for (0this.studentsSelected.size(); += 2)
  {
    
this.studentGroups.add({this.studentsSelected[i], this.studentsSelected[i+1]});
  }
  
  
// Remove incompatabilities
  
for (050i++)
  {
    
sGroup this.studentGroups[i];
    
    for (
0this.incompatability.size(); a++)
    {
      if ((
sGroup[0] == this.incompatability[a][0] || sGroup[0] == this.incompatability[a][1]) && (sGroup[1] == this.incompatability[a][0] || sGroup[1] == this.incompatability[a][1]))
      {
        echo(
"INCOMPATABILITY: " sGroup);
        
        
// we've found an incompatability, so lets flip this student with the next group
        
sGroup2 this.studentGroups[i+1];
        
        
sGroup[0] = sGroup2[0];
      }
    }
  }
  
  
this.end timevar2;
  
  echo(
this.end this.start);
  
  for (
050i++)
  {
    echo(
"Group " @ (i+1) @ ": {" this.studentGroups[i][0] @ ", " this.studentGroups[i][1] @ "}");
  }

Time taken: 0.002021789

Example Output:
PHP Code:
0.002021789
Group 1
: {137114}
Group 2: {282284}
Group 3: {47288}
Group 4: {26753}
Group 5: {19329}
Group 6: {345299}
Group 7: {141228}
Group 8: {9350}
Group 9: {347390}
Group 10: {166207}
Group 11: {13941}
Group 12: {130336}
Group 13: {140376}
Group 14: {262238}
Group 15: {1960}
Group 16: {35279}
Group 17: {368151}
Group 18: {54387}
Group 19: {81108}
Group 20: {332380}
Group 21: {249160}
Group 22: {73300}
Group 23: {6466}
Group 24: {316204}
Group 25: {24824}
Group 26: {8111}
Group 27: {215396}
Group 28: {252148}
Group 29: {270240}
Group 30: {229378}
Group 31: {172209}
Group 32: {227333}
Group 33: {283127}
Group 34: {42194}
Group 35: {359302}
Group 36: {6292}
Group 37: {30293}
Group 38: {105374}
Group 39: {371324}
Group 40: {242119}
Group 41: {83348}
Group 42: {256158}
Group 43: {189128}
Group 44: {232389}
Group 45: {322191}
Group 46: {225197}
Group 47: {33334}
Group 48: {239121}
Group 49: {39213}
Group 50: {23029
Probably not very efficient, but it works. I couldn't find any incompatibilities! XD
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Old 06-14-2008, 07:36 AM
Tolnaftate2004 Tolnaftate2004 is offline
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Quote:
Originally Posted by Programmer View Post
Probably not very efficient, but it works. I couldn't find any incompatibilities! XD
This does not test if switching 2 people forms compatibility...
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Old 06-14-2008, 07:44 AM
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Quote:
Originally Posted by Tolnaftate2004 View Post
This does not test if switching 2 people forms compatibility...
Picky, Picky.

PHP Code:
function onCreated()
{
  
this.start timevar2;
  
  
this.incompatability = {
    {
102284},
    {
392126},
    {
12},
    {
34},
    {
56},
    {
78}
  };
  
  
  
this.studentsSelected.clear();
  
this.studentGroups.clear();
  
  
numStudentsSelected 0;
  
// Select students at random
  
for (0100i++)
  {
    
int(random(0400));
    
    if (
this.studentsSelected.index(f) == -1)
    {
      
this.studentsSelected.add(f);
    } else
    {
      
i--; continue;
    }
  }
  
  
// Group them
  
for (0this.studentsSelected.size(); += 2)
  {
    
this.studentGroups.add({this.studentsSelected[i], this.studentsSelected[i+1]});
  }
  
  
// Remove incompatabilities
  
for (050i++)
  {
    
sGroup this.studentGroups[i];
    
    for (
0this.incompatability.size(); a++)
    {
      if ((
sGroup[0] == this.incompatability[a][0] || sGroup[0] == this.incompatability[a][1]) && (sGroup[1] == this.incompatability[a][0] || sGroup[1] == this.incompatability[a][1]))
      {
        echo(
"INCOMPATABILITY: " sGroup);
        
        
// we've found an incompatability, so lets flip this student with the next group
        
sGroup2 this.studentGroups[i+1];
        
        
sGroup[0] = sGroup2[0];
        
        
this.studentGroups[i] = sGroup;
        
this.studentGroups[i+1] = sGroup2;
        
        
i--;
        continue;
      }
    }
  }
  
  
this.end timevar2;
  
  echo(
this.end this.start);
  
  for (
050i++)
  {
    echo(
"Group " @ (i+1) @ ": {" this.studentGroups[i][0] @ ", " this.studentGroups[i][1] @ "}");
  }

Time: 0.001927852
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Old 06-14-2008, 08:46 AM
cbk1994 cbk1994 is offline
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Quote:
Originally Posted by Programmer View Post
Time: 0.001927852
Aww, mine was 0.008700847 seconds.

Of course, I was trying to make mine inefficient, for some reason ...
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Old 06-14-2008, 03:14 PM
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Quote:
Originally Posted by cbk1994 View Post
Aww, mine was 0.008700847 seconds.

Of course, I was trying to make mine inefficient, for some reason ...
Perhaps too many nested loops?
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Old 06-14-2008, 07:50 PM
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Quote:
Originally Posted by Programmer View Post
Picky, Picky.

PHP Code:
function onCreated()
{
  
this.start timevar2;
  
  
this.incompatability = {
    {
102284},
    {
392126},
    {
12},
    {
34},
    {
56},
    {
78}
  };
  
  
  
this.studentsSelected.clear();
  
this.studentGroups.clear();
  
  
numStudentsSelected 0;
  
// Select students at random
  
for (0100i++)
  {
    
int(random(0400));
    
    if (
this.studentsSelected.index(f) == -1)
    {
      
this.studentsSelected.add(f);
    } else
    {
      
i--; continue;
    }
  }
  
  
// Group them
  
for (0this.studentsSelected.size(); += 2)
  {
    
this.studentGroups.add({this.studentsSelected[i], this.studentsSelected[i+1]});
  }
  
  
// Remove incompatabilities
  
for (050i++)
  {
    
sGroup this.studentGroups[i];
    
    for (
0this.incompatability.size(); a++)
    {
      if ((
sGroup[0] == this.incompatability[a][0] || sGroup[0] == this.incompatability[a][1]) && (sGroup[1] == this.incompatability[a][0] || sGroup[1] == this.incompatability[a][1]))
      {
        echo(
"INCOMPATABILITY: " sGroup);
        
        
// we've found an incompatability, so lets flip this student with the next group
        
sGroup2 this.studentGroups[i+1];
        
        
sGroup[0] = sGroup2[0];
        
        
this.studentGroups[i] = sGroup;
        
this.studentGroups[i+1] = sGroup2;
        
        
i--;
        continue;
      }
    }
  }
  
  
this.end timevar2;
  
  echo(
this.end this.start);
  
  for (
050i++)
  {
    echo(
"Group " @ (i+1) @ ": {" this.studentGroups[i][0] @ ", " this.studentGroups[i][1] @ "}");
  }

Time: 0.001927852
Once again, this failed to perform the task.
Again, let's discuss what we ought to be doing to solve this problem. This is a very difficult problem to solve (HRs idea, don't blame me).
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Old 06-14-2008, 08:03 PM
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Quote:
Originally Posted by Tolnaftate2004 View Post
Today's challenge will include 2 problems:
  1. hard Suppose that you are organizing housing accommodations for a group of four hundred university students. Space is limited and only one hundred of the students will receive places in the dormitory. To complicate matters, the Dean has provided you with a list of pairs of incompatible students, and requested that no pair from this list appear in your final choice.
    The point of this exercise is to GENERATE DISCUSSION. We are not asking you to WRITE the code, merely speculate as to how you might do it. BUT IF YOU FEEL COMPELLED, write the code to accomodate arbitrary lists from the Dean.
  2. easy Solve this problem.
Is it possible for you to write in a little more simple English for me? I don't understand the task quite well, though I'd like to give it a go
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Old 06-14-2008, 08:20 PM
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Quote:
Originally Posted by Dan View Post
Is it possible for you to write in a little more simple English for me? I don't understand the task quite well, though I'd like to give it a go
1. hard You are putting 400 people in houses. Only 100 people will be able to have a house. You have a list of people that can not be in the same house. 2 people must be in each house. Talk about it, don't script it unless you want to.

Is that a bit better?
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Old 06-15-2008, 04:49 PM
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Not sure if I entirely understood the task, but I suppose this should work?

PHP Code:
function onCreated() {
  
temp.students_incompatible = {{1,2},{3,49}};
  
temp.students_total = new[400];
  
temp.house_list = {};
  
  while (
temp.house_list.size() < 100) {
    
temp.0;
    while (
temp.students_total[temp.i] == 1)
      
temp.++;
    
temp.students_total[temp.i] = 1;
    
temp.temp.i;
    
    
temp.go false;
    while (
temp.students_total[temp.j] == || !temp.go) {
      if ((@ {
temp.1,temp.1}) in temp.students_incompatible) {
        
temp.go false;
        
temp.++;
      }
      else if ((@ {
temp.1,temp.1}) in temp.students_incompatible) {
        
temp.go false;
        
temp.++;
      }
      else if (
temp.students_total[temp.j] == 1)
        
temp.++;
      else
        
temp.go true;
    }
    
temp.students_total[temp.j] = 1;
    
temp.house_list.add({temp.1,temp.1});
  }
  echo(
temp.house_list);

Time: 0.008579015
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  #22  
Old 06-15-2008, 05:39 PM
Chompy Chompy is offline
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Uhm, Dan, suppose to be discussion :o
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Old 06-15-2008, 06:33 PM
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Quote:
Originally Posted by Chompy View Post
Uhm, Dan, suppose to be discussion :o
Well then this is how I'd make the groups, lol.
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Old 06-15-2008, 06:35 PM
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Quote:
Originally Posted by Dan View Post
Well then this is how I'd make the groups, lol.
Try explain it with words instead of code
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Old 06-15-2008, 09:17 PM
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Quote:
Originally Posted by Chompy View Post
Try explain it with words instead of code
I want to know if it does what it should do tho (if I did what was needed).
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Old 06-16-2008, 07:36 PM
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You are using very small lists Your algorithms are based on the fact that the list is small. If you took your basic ideas and applied them to more complex or impossible lists, they would run much longer then any of our lifetimes.

By impossible, suppose you were given a list of incompatible students that makes it impossible to come up with 100 students.

Your work is cut out for you
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Old 06-16-2008, 10:41 PM
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Quote:
Originally Posted by Kristi View Post
If you took your basic ideas and applied them to more complex or impossible lists, they would run much longer then any of our lifetimes.
No, that's why we have a max loop limit
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Old 06-16-2008, 10:48 PM
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Quote:
Originally Posted by cbk1994 View Post
No, that's why we have a max loop limit
You are supposed to assume a limit doesn't exist (in graal this can be achieved with a scheduleevent).
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Old 06-16-2008, 11:03 PM
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Quote:
Originally Posted by Kristi View Post
You are supposed to assume a limit doesn't exist (in graal this can be achieved with a scheduleevent).
OK. Good luck to anyone trying, Dan's not going to invest any more time in this Programming Exercise because there's more work to do .
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  #30  
Old 06-18-2008, 10:46 PM
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Would this work?

PHP Code:
function onCreated()
{
  
this.start timevar2;
  
this.incompatability = {
                         {
23,46},
                         {
29,44},
                         {
45,96},
                         {
11,77},
                         {
2,32},
                         {
1,12},
                         {
13,69},
                         };
  
this.houselist NULL;
  for(
temp.i=0temp.i<100temp.i++)
  {
    
this.intA 0;
    
this.intB 0;
    while(!
this.intA && !this.intB)
    {
      
this.intA int(random(0,400));
      
this.intB int(random(0,400));
      for(
temp.j=0temp.j<100temp.j++)
      {
        if(
this.intA == this.houselist[temp.j][0])
          
this.int 0;
        else if(
this.intA == this.houselist[temp.j][1])
          
this.int 0;
        else if(
this.intB == this.houselist[temp.j][0])
          
this.int 0;
        else if(
this.intB == this.houselist[temp.j][1])
          
this.int 0;
        if(
this.intA == this.incompatibility[temp.j])
          if(
this.intB == this.incompatibility[temp.j])
            
this.int 0;
        else if(
this.intB == this.incompatibility[temp.j])
          if(
this.intA == this.incompatibility[temp.j])
            
this.int 0;
      }
      if(
this.intA == this.intB)
        
this.int 0;
    }
    
this.houselist.add({this.intA,this.intB});
  }
  
this.end timevar2;
}
savelog2("houseList.txt",this.houselist);
echo(
"Time: " this.end this.start); 
Time: 0.026829004

Damn that's slow compared to others lol
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Old 06-18-2008, 11:00 PM
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Quote:
Originally Posted by Stryke View Post
Would this work?

PHP Code:
function onCreated()
{
  
this.start timevar2;
  
this.incompatability = {
                         {
23,46},
                         {
29,44},
                         {
45,96},
                         {
11,77},
                         {
2,32},
                         {
1,12},
                         {
13,69},
                         };
  
this.houselist NULL;
  for(
temp.i=0temp.i<100temp.i++)
  {
    
this.intA 0;
    
this.intB 0;
    while(!
this.intA && !this.intB)
    {
      
this.intA int(random(0,400));
      
this.intB int(random(0,400));
      for(
temp.j=0temp.j<100temp.j++)
      {
        if(
this.intA == this.houselist[temp.j][0])
          
this.int 0;
        else if(
this.intA == this.houselist[temp.j][1])
          
this.int 0;
        else if(
this.intB == this.houselist[temp.j][0])
          
this.int 0;
        else if(
this.intB == this.houselist[temp.j][1])
          
this.int 0;
        if(
this.intA == this.incompatibility[temp.j])
          if(
this.intB == this.incompatibility[temp.j])
            
this.int 0;
        else if(
this.intB == this.incompatibility[temp.j])
          if(
this.intA == this.incompatibility[temp.j])
            
this.int 0;
      }
      if(
this.intA == this.intB)
        
this.int 0;
    }
    
this.houselist.add({this.intA,this.intB});
  }
  
this.end timevar2;
}
savelog2("houseList.txt",this.houselist);
echo(
"Time: " this.end this.start); 
Time: 0.026829004

Damn that's slow compared to others lol
I didn't try it, but, like said, anything using random will not work well with larger numbers.
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  #32  
Old 06-18-2008, 11:00 PM
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I think it's slow because of the logging you're doing. But yeah, quite some loops also.
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  #33  
Old 06-21-2008, 06:36 AM
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Oh it's only 50? :P

Time remaining: 0.007151126

Still crappy. :P I took out the log too.
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  #34  
Old 06-21-2008, 06:52 PM
Tolnaftate2004 Tolnaftate2004 is offline
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We can assume that the algorithm would eventually need to be used to find an appropriate room assignment for a group of students for which there is only one solution (i.e. worst case scenario). Because of this, the algorithm would need to "know" that student A needs to pair with student B rather than student C. Hence why random is a horrible idea.
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Old 07-19-2008, 09:26 PM
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PHP Code:
//#CLIENTSIDE
function onWeaponFired() {
  
// Bad match array
  
temp.bad = {
             {
91,50},
             {
60,230},
             {
132,399},
             {
52,293},
             {
22,25},
             {
83,293},
             {
83,82}
             };
  
// Generate students array
  
temp.students = new[400];
  for (
temp.0temp.400temp.i++)
    
temp.students[temp.i] = temp.i;



  
// START of exercise
  
temp.start timevar2;

  
// Shuffle students array
  
temp.temp.students.size();
  for (
temp.0temp.temp.1temp.i++) {
    
temp.temp.random(0,32767) / (32767 / (temp.temp.i) + 1);
    
temp.temp.students[temp.j];
    
temp.students[temp.j] = temp.students[temp.i];
    
temp.students[temp.i] = temp.t;
  }
  
  
// Heapsort the bad match array
  
temp.bad.sortascending();
  
  
temp.pairs = new[50];
  
temp.0;
  while (
temp.50) {
    
temp.pair = {temp.students[temp.x], temp.students[temp.x+1]};

    
// Binary search for the current pair in the bad pairs
    
if (binarysearcharray(temp.badtemp.pair) == -1) {
      
temp.pairs[temp.i] = temp.pair;
      
temp.x++;
    }
    
temp.x++;
    
temp.i++;
  }
  
  
  
// END of exercise
  
temp.time timevar2 temp.start;
    
  
player.chat temp.pairs;
  echo (
temp.time);
}

// Modified binary search
function binarysearcharray(temp.atemp.v) {
  
temp.low 0;
  
temp.high temp.a.size()-1;
  while (
temp.low <= temp.high) {
    
temp.mid = (temp.low temp.high) /2;
    if (
temp.a[temp.mid][0] > temp.v[0] || temp.a[temp.mid][0] == temp.v[0] && temp.a[temp.mid][1] > temp.v[1]) 
      
temp.high temp.mid 1;
    else if (
temp.a[temp.mid][0] < temp.v[0] || temp.a[temp.mid][0] == temp.v[0] && temp.a[temp.mid][1] < temp.v[1])
      
temp.low temp.mid +1;
    else
      return 
temp.mid;
  }
  return -
1;

Average running time of 0.00326736083, but it's a rather small "bad pair" set.

Should run in O(n log n log m) where n is the number of pairs and m is the number of bad pairs.

Last edited by WhiteDragon; 07-20-2008 at 09:20 PM.. Reason: Slight mistake
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  #36  
Old 07-21-2008, 07:47 AM
WhiteDragon WhiteDragon is offline
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I realized I made an error, but it wouldn't let me edit it... so here is another giant block of code:

PHP Code:
//#CLIENTSIDE
function onWeaponFired() {
  
// Bad match array
  
temp.bad = {
             {
91,50},
             {
60,230},
             {
132,399},
             {
52,293},
             {
22,25},
             {
83,293},
             {
83,82}
             };
  
// Generate students array
  
temp.students = new[400];
  for (
temp.0temp.400temp.i++)
    
temp.students[temp.i] = temp.i;



  
// START of exercise
  
temp.start timevar2;

  
// Shuffle students array
  
temp.temp.students.size();
  for (
temp.0temp.temp.1temp.i++) {
    
temp.temp.random(0,32767) / (32767 / (temp.temp.i) + 1);
    
temp.temp.students[temp.j];
    
temp.students[temp.j] = temp.students[temp.i];
    
temp.students[temp.i] = temp.t;
  }
  
  
// Heapsort the bad match array
  
temp.bad.sortascending();
  
  
temp.pairs = new[50];
  
temp.0;
  while (
temp.50) {
    
temp.pair = {temp.students[temp.x], temp.students[temp.x+1]};

    
// Binary search for the current pair in the bad pairs
    
if (binarysearcharray(temp.badtemp.pair) == -1) {
      
// Add it
      
temp.pairs[temp.i] = temp.pair;
      
temp.students.remove(temp.students[temp.x]);
      
temp.students.remove(temp.students[temp.y]);
      
temp.i++;
      
temp.0;
      
temp.0;
    } else {
      
// Look more
      
if (temp.== temp.students.size()) {
        
temp.x++;
        
temp.0;
      } else {
        
temp.y++;
      }
    }
  }
  
  
  
// END of exercise
  
temp.time timevar2 temp.start;
    
  
player.chat temp.pairs;
  echo (
temp.time);
}

// Modified binary search
function binarysearcharray(temp.atemp.v) {
  
temp.low 0;
  
temp.high temp.a.size()-1;
  while (
temp.low <= temp.high) {
    
temp.mid = (temp.low temp.high) /2;
    if (
temp.a[temp.mid][0] > temp.v[0] || temp.a[temp.mid][0] == temp.v[0] && temp.a[temp.mid][1] > temp.v[1]) 
      
temp.high temp.mid 1;
    else if (
temp.a[temp.mid][0] < temp.v[0] || temp.a[temp.mid][0] == temp.v[0] && temp.a[temp.mid][1] < temp.v[1])
      
temp.low temp.mid +1;
    else
      return 
temp.mid;
  }
  return -
1;

Worst case is actually O(n**2 log n log m), but it uses Randomization and Restriction, so it's considerably fast than the worst case.
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  #37  
Old 08-02-2008, 11:24 AM
_Z3phyr_ _Z3phyr_ is offline
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Quote:
Originally Posted by Tolnaftate2004 View Post
Today's challenge will include 2 problems:
  1. hard Suppose that you are organizing housing accommodations for a group of four hundred university students. Space is limited and only one hundred of the students will receive places in the dormitory. To complicate matters, the Dean has provided you with a list of pairs of incompatible students, and requested that no pair from this list appear in your final choice.
    The point of this exercise is to GENERATE DISCUSSION. We are not asking you to WRITE the code, merely speculate as to how you might do it. BUT IF YOU FEEL COMPELLED, write the code to accomodate arbitrary lists from the Dean.

Note From Hell Raven: the 100 students are rooming in pairs of 2. So that is 50 pairs (I do not believe this was clear...)

answer:





proof:

N and B are disjoint sets. (see above picture)

---

this is an abstract problem. idk what you guys have been doing with all of that prime number crap.

Last edited by _Z3phyr_; 08-02-2008 at 01:40 PM..
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  #38  
Old 08-02-2008, 10:35 PM
WhiteDragon WhiteDragon is offline
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This problem is NP-complete, so it's impossible to do it in polynomial time.
The runtime is actually O(n**m) if you check all conditions. The best way to attack the problem would most likely be dynamic programming.
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