If this is the case Phil, then you need to be generating a random set of integers from 1 to 9, not a sequence of integers from 1 to 9:
input should be a list of numbers from 1 to 9 generated randomly that can repeat
output should be a list of numbers from 1 to 9 that do not repeat
// v is always: 1 2 3 4 5 6 7 8 9 (no duplicates, ever) for(int i=1;i<10;i++) v.push_back(i); random_shuffle(v.begin(),v.end()); // (elements might be in a random order, but there still aren't any duplicates) // v could be: 9 1 8 6 7 4 6 3 2 for(int i=1;i<10;i++) v.push_back( rand()%9 + 1 ); // (may have duplicates)(See the reference on rand. rand() returns an integer between 0 and RAND_MAX -- usually 32767 -- and the modulus wraps that around the range between 0 and 8, and adding one brings it between 1 and 9.)
Then, you'll need to include algorithm, such that you can use sort to move duplicates together, then use unique to move the duplicate values to the back. Once the unique values are in front, you can remove the duplicates from v by using the iterator returned by unique:
sort( v.begin(), v.end() ); v.erase( unique(v.begin(),v.end()), v.end() );
Hurr durr, I read can documentation good.