# Generating a combination of strings

I am looking for opitmal method of generating pair of numbers from string number.
For example string 12345
Should produce: 11 12 13 14 15 22 23 24 25 33 34 35 44 45 55
or
String 121256708
Should produce: 11 12 15 16 17 10 18 22 21 25 26 27 20 28 55 56 57 50 58 66 67 60 68 77 70 78 00 08 88

I've perused the STL algorithms but I'm coming up short on the right combination - if you will.
Idea.

Thanks in advance
Asked:
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Commented:
Hey, try this:

#include <iostream>
#include <string>
#include <deque>
using namespace std;

int main()
{
string model;
cout << "enter string: ";
cin >> model;
deque<string> pairs;
string a;
for (int i=0; i< model.size(); i++)
for (int j=i; j< model.size(); j++)
{
a = "";
a+=model[i];
a+=model[j];
pairs.push_back(a);
}

for (int i=0; i< pairs.size(); i++)
cout << pairs[i] << " ";
cout << endl;
return 1;
}
0
Author Commented:

Your approach doesnt remove duplicates, nonetheless, I had something similar.  I thought perhaps there was a more elegant approach in the form of STL algorithms.
0
Commented:
well, if you want to remove duplicates, an easy way to do it would be to use a <set> instead of a <deque> ... A set is a collection of unique variables, so if you try to insert something that already exists, it won't get inserted twice...

the only difference in the code would be that you would need an iterator to go through the set

set<string> pairs;

... code to load up the set ...

for ( set<string>::iterator t = pairs.begin(), t!= pairs.end(); t++)
{
cout << *t << " ";
cout << endl;
return1;
}

Now, if you consider "21" and "12" a duplicate pair, and you want to watch out for that as well, what you could do is sort the string before you insert it into the set... this can be accomplished like this

#include <algorithm>

sort ( a );
pairs.push_back(a);

hope this helps,

Gustavo.
0

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