Where can you implement recursion

Question

Where can you use recursion? Give examples.

Answer 1

I submitted a lesson to do everything using recursion. This program contains the details and is my implementation for it. It is coded in Kotlin, but should be understandable to you.
https://code.sololearn.com/c0g34cgteZjA

Answer 2

Recursion is when a function calls upon itself again and again with a given base case to terminate.

Like if you're given to find the factorial of a given number using recursion...
It can be done like

#define the function
def fact(n):
# it's the base case
if n<1 and n>=0:
return 1
else:
#this is the recursive call
return n*fact(n-1)

This is in python but you can implement the same in any language.

Answer 3

If you just know how the recursion works and what should be the base case then you can use it in many areas. The above example was just to show you what recursion is.
Having idea of recursion, you can implement it in many problems, like on some GUI as well.
Other common use cases might include sorting data, traversing hierarchies, e.g. website crawlers, directory comparisons, etc.

Of course, one can always use loops to do the same thing but recursion makes the code shorter to implement.

Answer 4

How else could you use it apart from factorial and numbers?

Answer 5

You can use recursion practically on every problem that can be broken into smaller problems of the same kind. In other words, problems that you can state with a recursive description:

You have already seen:
factorial(n) = n * factorial(n-1)

Merge sort:
sort(array) =
1. sort(left half of array)
2. sort(right half of array)
3. merge
here sorting the full array is solved by solving the problem for the left and right halves of the same array

Tree walks:
(e.g.) in-order(whole tree) =
in-order(left-branch)
operate-on(root)
in-order(right-branch)
a branch is again a tree but smaller in size.

You see the general pattern, i guess. If you can express the solution of your problem in terms of the solutions to the same problem of a smaller size, recursion is applicable.

Answer 6

Most loops could be replaced by a recursive function, some problems are easier to solve with a recursive function, such as printing all the elements​ of binary tree in order.