Understand tail recursion

General recursive form
Int fun (int n) {<br/> if (n = 0) return 0; <br/> return n + fun (n-1); <br/>}
Mathematical model:

N = 0 0

N! = 0 f (n)


General Form of tail recursion
Int fun (int sum, int n) {<br/> if (n = 0) return sum; <br/> return fun (sum + n, n-1 ); <br/>}

 

Comparison of Two recursive forms:

Recursion: f (n). The return value is used by the caller.

Tail recursion: f (m, n). The return value is not used by the caller.

In-depth comparison of the two types of recursion:

Due to the direct return value, tail recursion does not need to save temporary variables, so performance will not increase linearly. In addition, the compiler optimizes tail recursion to non-recursion.