Recursion

What is recursion?

Recursion is an algorithm that calls itself on an ever reducing/simplifying version of itself/its dataset.

At its core, a recursive algorithm consists of:

• the base case (the exit condition)
• recursive case (the condition that keeps simplifying the dataset)

Example

Counting down from n while reducing n on each recursive call.

start = 10
countDown = func(n) {
    // If we've reached our target n, exit i.e. the base case
    if n < 0 {
        return
    }
    println(n)

    // Reduce/simplify the dataset i.e. the recursive case
    countDown(n-1)
}
countDown(10)

And in Go:

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package main

func main() {
	var countDown func(i int)
	countDown = func(i int) {
		// If we've reached our target n, exit i.e. the base case
		if i < 0 {
			return
		}

		println(i)

		// Reduce/simplify the dataset i.e. the recursive case
		countDown(i - 1)
	}
	countDown(10)
}

/*
10
9
8
7
6
5
4
3
2
1
0
*/