Daily Coding Problem: Problem #5

problem5.py

"""
This problem was asked by Jane Street.

cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first and last element of that pair. For example, car(cons(3, 4)) returns 3, and cdr(cons(3, 4)) returns 4.

Given this implementation of cons:

def cons(a, b):
    return lambda f : f(a, b)
Implement car and cdr.

https://dailycodingproblem.com/
"""

def cons(a, b):
	return lambda f: f(a, b)

def car(f):
	return f(lambda a, b: a)

def cdr(f):
	return f(lambda a, b: b)

if __name__ == '__main__':
	# Read input of two numbers, separated by commas
	a, b = (int(n) for n in input().split(','))
	print(car(cons(a, b)))
	print(cdr(cons(a, b)))