Question

Considering an array a[i], i=0,1,...,g, where g could be any given number, and a[0]=1.

for a[1]=a[0]+1 to 1 do
   for a[2]=a[1]+1 to 3 do
      for a[3]=a[2]+1 to 5 do
         ...
            for a[g]=a[g-1]+1 to 2g-1 do
               #print a[1],a[2],...a[g]#

The problem is that everytime we change the value of g, we need to modify the code, those loops above. This is not a good code.

Answer 1

Recursion is one way to solve this(although I was love to see an iterative solution).

!!! Warning, untested code below !!!

template<typename A, unsigned int Size>
void recurse(A (&arr)[Size],int level, int g)
{
   if (level > g) 
   { 
     // I am at the bottom level, do stuff here
     return;
   }

   for (arr[level] = arr[level-1]+1; arr[level] < 2 * level -1; arr[level]++)
   {

      recurse(copy,level+1,g);
   }
}

Then call with recurse(arr,1,g);