combinations of elements on vectors

cpit · #1 27-Sep-2006, 12:12

Hi friends,

I have a vector x={1,2,2} and I want to obtain its combinations

i.e.
y={{1,1,1},{1,1,2},{1,2,1},{1,2,2}}

Here is a sample of the program, we can see the amount of combinations with this...

CPP / C++ / C Code:

#include <iostream>
#include <vector>

using namespace std;

int main(){

vector<int> mroute;

mroute.push_back(1);
mroute.push_back(2);
mroute.push_back(2);

//To find the number of combinations
int ncombs=1;

for(int i=0;i<mroute.size();i++){
        if(mroute[i]>0){
            ncombs*=mroute[i];               
        }
}
cout << "Number of combinations: " <<ncombs<<endl;

//--- to print the combinations! ----------------

system("PAUSE");    
}

Can someone give a suggestion to do it?

regards,

CPIT

MichaelS-R · #2 28-Sep-2006, 04:47

Hmmm... bit lost here. How is {1,1,1} a combination of {1,2,2}? What are you using the results for?

cpit · #3 28-Sep-2006, 05:36

OK Friend,
I will try to explain better...

I´m going use this for to implement all possible routes in a network.

I made a modification on Dijkstra´s algorithm to find all shortest paths between two nodes.

Then, imagine a network with 4nodes and connected like this:

1-2 or be, node1 have a link to connect node2...
1-3
2-4
3-4

After perform the algorithm to find out all shortest paths we have 2 routes from the node 1 to node 4, and 2 routes from the node 2 to 3.

then, we can set a matrix of paths like this:

- 1 1 2
1 - 2 1
1 2 - 1
2 1 1 -

and using the number above the main diagonal, we have 1 1 2 2 1 1

Now I need to perform other calcs on each combination of traffic.

then 1 1 1 1 1 1 means that I will use a set of paths
and 1 1 1 2 1 1 means that I will use other set of paths
and 1 1 2 1 1 1
and 1 1 2 2 1 1

In this simple case we have only 4 combinations, but I want to tread large networks, for example, with more than 100 nodes!!!

Regards,

CPIT

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combinations of elements on vectors

Re: combinations of elements on vectors

Re: combinations of elements on vectors