Recursion of Python

Tag: is the tail recursive efficiency stack Overflow save optimization return problem condition

Recursion is the function that calls this function internally.

Characteristics of recursion:

1. There must be a definite end condition, otherwise it will turn into a dead loop, the final detonation system.

2. Each time you enter a deeper level of recursion, the problem size should be reduced compared to the previous recursion.

3. Recursive execution is inefficient, and too many recursive hierarchies can cause stack overflow.

Example: Recursion

def factorial (n):
If n==1:
Return 1
Return N*factorial (n-1)

Print (factorial (4)) #输出4的阶乘

Tail-Recursive optimization:

def CAL (N):
Print (n)
Return Cal (N+1)
Cal ()

The variables and contents of the functions executed at each recursive time are not saved in the stack, so the recursive stack is not full.

Recursion of Python