I need to insert a small logo where I can convey that code can think or thinking code.
Is there way to represent that in very small logo form?
I'm always partial to a silhouette of a human head with a microchip in it, but this likely won't work for a "very small" icon.
What level of thinking is your code doing? Does the icon represent "do some incredibly complex heuristics", or does it just represent "make the code do the thinking for me". Depending on the associated action, you could do a pictorial representation of a decision tree - something as simple as a few lines and small boxes arranged in a flowchart may work for this.