Exiting a recursive function at the topmost level in C ++

You can use exceptions for this - either throw some suitable exception or create your own and use it. While using exceptions for flow control is generally not recommended, it is the only reliable way here.

The question is, how did you get there? Which algorithm buries you deeply in recursion without being able to get out of it?

Any recursive function must have a way to terminate the recursion, it only recurses if the condition is either true or false. When this fails, the recursion ends and the function returns instead of recursing deeper.
Why don't you just end up recursion this way, going back through all the levels?

If you're desperate, exception is the way to go, but it's (rightfully so IMO) frowned upon.

Make your function optimized. Then there are no "functions above" to worry about.

No, you cannot reverse your recursion and go straight back to your main (). If your recursive function does not do different work after the recursive call, you would effectively do the same thing. I recommend restructuring a recursive function. A description of why you want to break out of recursion early on will also be helpful.