functii.py

#Decomposition is segmenting the code into smaller parts, for easier reading and maintenance
def numeFunctie():
	return "Nu printez doar returnez"
rezultat = numeFunctie()
print(rezultat)
print(type(rezultat)) #e str

def functie2():
	return 'lorin salam', 2
print(functie2())
print(type(functie2())) #e tupla

#acum pun si parametrii
def fun3(a,b):
	c= a+b
	return c
rezultatul = fun3(12,3)
print(rezultatul)

#poti avea valori default pt parametrii
#parametri cu valori default ar trebui pusi ultimii
def default_parameter(a, b=4, c=5):
	return a+b+c
rezult2 = default_parameter(3) #a=3
print(rezult2)

#SCOPE is like the range of use of a parameter inside a function
#parametrii sunt valabili DOAR IN INTERIOR FUNCTIE
def scope2(a):
	a +=1
	print(a)
	return a
print(scope2(5))
#can't call a outside the function
#print(a) #ar da eroare

#NESTED FUNCTIONS = functie intr-o functie
#a scope of a nested function is only within the parent function
#cu nested func tre sa folosesti ; 
def outer_fun(a):

	def nested_fun(b):
		return b * a;
	a = nested_fun(a)
	return a
print(outer_fun(4)) #prints 16

def f(a):
	def g(b):
		def h(c):
			return a*b*c
		return h
	return g
print(f(5)(2)(3)) #prints 30
#5 e pt outer function, f
#2 e pt nested function, g
#3 e pt nested function, h

#RECURSIVE functions
#break down a problem into subproblems 
#it's a function calling itself, over and over again
#daca n nu este unu, va face else-ul de mai multe ori
#doar cand n =1  face return si iesi din functie, respectiv din 'loop'
def factorial(n):
	if n == 1:
		return 1 #pt a iesi din recursion
	else:
		return n * factorial(n-1) #am folosit aceeasi functie in functia respectiva => recursion
print(factorial(5)) #prints 120
# 5*4*3*2*1 = 120
#In mathematics, the factorial of a non-negative integer n, denoted by n!, 
#is the product of all positive integers less than or equal to n. For example,
#  5! = 5 × 4 × 3 × 2 × 1 = 120. 

#we have REGULAR and TAIL recursion

#REGULAR recursion:
def summ(n):
	if n == 1:
		return 1 #pt a iesi din recursion cand ajunge la 1
	else:
		return n + summ(n-1)
print(summ(10))
# 10+9+8+7+6+5+4+3+2+1 = 55

#TAIL recursion:
def tail_sum(n, accumulator = 0):
	if n==0:
		return accumulator
	else:
		return tail_sum(n-1, accumulator+n)
print(tail_sum(10)) #prints 55