'''
    recursion.py
    Jeff Ondich, 2 November 2018

    A few recursive functions for discussion and
    experimentation in CS111, Fall 2018.
'''
import sys

def factorial(n):
    if n <= 1:
        result = 1
    else:
        a = factorial(n - 1)
        result = n * a
    return result

def fibonacci(n):
    if n <= 2:
        result = 1
    else:
        a = fibonacci(n - 1)
        b = fibonacci(n - 2)
        result = a + b
    return result

def reverse_string(s):
    if s == '':
        result = ''
    else:
        a = reverse_string(s[1:])
        result = a + s[0]
    return result

def e_count(s):
    print('e_count({0})'.format(s))
    count = 0
    if s != '':
        count = e_count(s[1:]) # count e's in the tail
        if s[0] == 'e':
            count = count + 1
    print('e_count({0}) = {1}'.format(s, count))
    return count

def infinite_recursion(n):
    print('infinite_recursion({0})'.format(n))
    return infinite_recursion(n - 1)

def infinite_loop(n):
    print('infinite_loop({0})'.format(n))
    while True:
        print(n)
        n = n - 1
    
#n = int(sys.argv[1])
#result = fibonacci(n)
#print('fib({0}) = {1}'.format(n, result))

#s = sys.argv[1]
#count = e_count(s)
#print('The number of e\'s in "{0}" is {1}'.format(s, count))