Question

Python

#Remember that Fibonacci's sequence is a sequence of numbers
#where every number is the sum of the previous two numbers.
#
#Joynernacci numbers are similar to Fibonacci numbers, but
#with two differences:
#
# - Fibonacci numbers are famous, Joynernacci numbers are
# not (yet).
# - In Joynernacci numbers, even-indexed numbers are the
# sum of the previous two numbers, while odd-indexed
# numbers are the absolute value of the difference
# between the previous two numbers.
#
#For example: the Joynernacci sequence starts with 1 and 1
#as the numbers at index 1 and 2. 3 is an odd index, so
#the third number would be 0 (1 - 1 = 0). 4 is an even
#index, so the fourth number would be 1 (0 + 1). 5 is an
#odd index, so the fifth number would be 1 (1 - 0). And
#so on.
#
#The first several Joynernacci numbers (and their indices)
#are thus:
#
# 1 1 0 1 1 2 1 3 2 5 3 8 5 13 8 21 13 34 21
# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
#
#Write a function called joynernacci that returns the nth
#Joynernacci number. For example:
#
# joynernacci(5) -> 1
# joynernacci(12) -> 8
#
#We recommend implementing joynernacci recursively, but it
#is not required.

#Write your code here!

#Below are some lines of code that will test your function.
#You can change the value of the variable(s) to test your
#function with different inputs.
#
#If your function works correctly, this will originally
#print: 1, then 8
print(joynernacci(5))
print(joynernacci(12))

Answer 1

The function joyernacci can be defined as follows:

• Use def joyernacci(n) as the function signature. n is the index of the term that has to be printed.
• Create an empty list.
• Append 0, 1 and 1 to the list.
• Use a for loop, which will start at position 3 until n+1.
• For the term whose index is even, the value is addition of previous two terms.
• For the term whose index is odd, the value is the absolute value of the difference of previous two terms.
• Print the nth term of the list

The python program:

#function to return the nth joynernacci term
def joynernacci(n):
    l = []
    l.append(0)    #0 at 0th index
    l.append(1)    #1 at 1st index
    l.append(1)    #2 at 2nd index
    
    #computing terms for index 3 to n
    for i in range(3,n+1):
        #for even terms
        if (i)%2==0:
            l.append(l[i-1] + l[i-2])
        #for odd terms
        else:
            l.append(abs((l[i-1]) - l[i-2]))
      
    #print the nth 
    print(l[n])
        
#call function for 5th term
joynernacci(5)

#call function for 12th term
joynernacci(12)

Here is the code sippet to understand the indentation:

Output:

Code in jupyter with output: