code:

depth = 5;
s = new stack();
leaves = new queue();
State current = (current state);
s.push(current);
while(s not empty)
{
    current = s.pop();
    depth--;
    nextMoves = (possible moves from current)
    for(move in nextMoves)
    {
         State new = transitionState(current, move);
         if (depth==0)
         {
              leaves.push(new);
              depth++;
         }
         else s.push(new);

    }
}