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I am currently working on a program in C, that needs to calculate the permutations
of a n integer array. The approach that I have taken is using recursion, using a n-element array of counters incrementing the correct value each recursion,
so the subroutine calls itself x (x being the max # of permutations) number of times returning the next permutation.
For example: Information known ahead of time: n = 3(could be any value); n_array[0] = 3 (could be any value from 1 to 9), n_array[1] = 3, n_array[2] = 3:
so first permutation (does not have to be in this order):
0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
1 0 0
1 0 1
1 0 1
1 1 1 etc.
That being said, I attempted to write a loop within the recursive function that looks like this,
which gives the following:
0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
0 3 0 -> incorrect
1 0 1
1 0 2 etc.
I realize what my loop is doing, but I can't think of a way to fix
it, any fresh ideas would be appriciated. Thanks in advance.
of a n integer array. The approach that I have taken is using recursion, using a n-element array of counters incrementing the correct value each recursion,
so the subroutine calls itself x (x being the max # of permutations) number of times returning the next permutation.
For example: Information known ahead of time: n = 3(could be any value); n_array[0] = 3 (could be any value from 1 to 9), n_array[1] = 3, n_array[2] = 3:
so first permutation (does not have to be in this order):
0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
1 0 0
1 0 1
1 0 1
1 1 1 etc.
That being said, I attempted to write a loop within the recursive function that looks like this,
for(i = 0; i <n; i++) {
if(i == n-1) {
count[i]++;
}
if(count[i] == n_array[i]) {
count[i] = 0;
count[i-1]++;
}
}0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
0 3 0 -> incorrect
1 0 1
1 0 2 etc.
I realize what my loop is doing, but I can't think of a way to fix
it, any fresh ideas would be appriciated. Thanks in advance.
Last edited by WaltP : Nov 10th, 2006 at 2:02 am. Reason: Use regular CODE tags, not INLINECODE tags for code blocks
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this would be in the daniweb code snippet section.
I'm not a programmer. My attitude starts with ignorance, holds steady at conversation, and ends with a trip to the hospital. Get used to it.
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Originally Posted by iamthwee 
this would be in the daniweb code snippet section.
Under what listing, I went through all snippets, and I did not see what I was looking for.
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I'm not a programmer. My attitude starts with ignorance, holds steady at conversation, and ends with a trip to the hospital. Get used to it.
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Join Date: Jun 2006
Location: India
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I don't accept change. I don't deserve to live.
Happiness corrupts people.
Failing to value the lives of others cheapens your own.
Happiness corrupts people.
Failing to value the lives of others cheapens your own.
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Originally Posted by ~s.o.s~
A non recursive way, if it suits your need:
http://www.daniweb.com/code/snippet533.html
Not what I am looking for, look at my first post.
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Originally Posted by merck120
Not what I am looking for, look at my first post.
So, your example don't even make sense
0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
1 0 0
1 0 1 <- Why the repeat
1 0 1 <-Why the repeat
1 1 1
In fact your example doesn't even exhibit behaviour you would expect when using the word 'permutation'
Last edited by iamthwee : Nov 10th, 2006 at 2:29 pm.
I'm not a programmer. My attitude starts with ignorance, holds steady at conversation, and ends with a trip to the hospital. Get used to it.
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Originally Posted by iamthwee
So, your example don't even make sense
0 0 0
0 0 1
0 0 2
0 1 0
0 1 1
0 1 2
0 2 0
0 2 1
0 2 2
1 0 0
1 0 1 <- Why the repeat
1 0 1 <-Why the repeat
1 1 1
In fact your example doesn't even exhibit behaviour you would expect when using the word 'permutation'
I sorry, that line is a typo, and it should not be repeated, and yeah I know permutation is not the best word, for what I am doing, combinations, would probably be better.
it should be:
100
101
102
110
etc.
Last edited by merck120 : Nov 10th, 2006 at 2:34 pm.
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Ok, so do you mean the mathematical definition of the word combination.
Or are you going to change your mind again.
Or are you going to change your mind again.
I'm not a programmer. My attitude starts with ignorance, holds steady at conversation, and ends with a trip to the hospital. Get used to it.
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Originally Posted by iamthwee
Ok, so do you mean the mathematical definition of the word combination.
Or are you going to change your mind again.
Yes, all of the mathematical combinations, per my fixed example.
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