day17(Recursions).py

# function ke andar usse same  fuction ko call krte  
# factorial(7) = 7*6*5*4*3*2*1
# factorial(6) = 6*5*4*3*2*1
# factorial(5) = 5*4*3*2*1
# factorial(4) = 4*3*2*1
# factorial(0) = 1


# factorial(n) = n * factorial(n-1)
def factorial(n):
    if(n==0 or n==1):
        return 1
    else:
        return(n* factorial(n-1))
print(factorial(4))
print(factorial(2))
print(factorial(0))
# 5 * factorial(4)
# 5 * 4 * factorial(3)
# 5 * 4 * 3 * factorial(2)
# 5 * 4 * 3 * 2 * factorial(1)
# 5 * 4 * 3 * 2 * 1
#FIBBONACCI SERIES
# f(0) = 0
# f(1) = 1
# f(2) = f(1) + f(0)
# f(n) = f(n-1) + f(n-2)
# 0 1 1 2 3 5 8....
def Fibbonacci(n):
    if(n==0):
     return 0
    elif(n==1):
       return 1
    else:
       return(Fibbonacci(n-1)+Fibbonacci(n-2))
print(Fibbonacci(3))
print(Fibbonacci(0))
print(Fibbonacci(1))
print(Fibbonacci(2))
print(Fibbonacci(5))