Recursion is a tree, with branches and leaves, called parents and children respectively. When you use a recursion algorithm, you more or less consciously are building a tree from the data.
0 Recursion and iteration are different ways to think about a solution. It would be dificult to explain in depth the difference in full scope. In your sample code, you aleady showed the difference. Recursive function is the one that calls itself, while iterative is the one that loops through some block of code.
Recursion is used to express an algorithm that is naturally recursive in a form that is more easily understandable. A "naturally recursive" algorithm is one where the answer is built from the answers to smaller sub-problems which are in turn built from the answers to yet smaller sub-problems, etc.
Tail Call Recursion Once you understand how the above recursion works, you can try to make it a little bit better. Now, to find the actual result, we are depending on the value of the previous function also. The return statement cannot immediately return the value till the recursive call returns a result.
Is it correct to say that everywhere recursion is used a for loop could be used? And if recursion is usually slower what is the technical reason for ever using it over for loop iteration? And if i...
19 Recursion is more costly in memory, as each recursive call generally requires a memory address to be pushed to the stack - so that later the program could return to that point. Still, there are many cases in which recursion is a lot more natural and readable than loops - like when working with trees.
Well, in general, recursion can be mimicked as iteration by simply using a storage variable. Note that recursion and iteration are generally equivalent; one can almost always be converted to the other. A tail-recursive function is very easily converted to an iterative one. Just make the accumulator variable a local one, and iterate instead of ...
Recursion started making sense to me when I stopped reading what others say about it or seeing it as something I can avoid and just wrote code. I found a problem with a solution and tried to duplicate the solution without looking.
Why? Because recursion is typically well founded over some data structure, inducing an Initial F-algebra and allowing you to prove some properties about termination along with inductive arguments about the structure of the (recursive) computation. The process by which recursion is compiled to loops is tail call optimization.
