def make_rat(n, d):
# return cons(n, d)
g = gcd(abs(n), abs(d))
sign = 1
if n < 0 and d >= 0 or d < 0 and n >= 0:
sign = -1
return cons(int(abs(n / g) * sign), int(abs(d / g)))
def make_interval(a, b):
return cons(a, b)
def make_segment(start, end):
return cons(start, end)
def midpoint_segment(segment):
return cons(
average(x_point(start_segment(segment)),
x_point(end_segment(segment))),
average(y_point(start_segment(segment)),
y_point(end_segment(segment))))
def make_point(x, y):
return cons(x, y)
def make_rectangle_2(left_top, x, y):
return cons(left_top,
make_point(x_point(left_top) + x,
y_point(left_top) - y))
def make_rectangle(left_top, right_bottom):
return cons(left_top, right_bottom)
def append(list1, list2):
if null(list1):
return list2
return cons(car(list1), append(cdr(list1), list2))
from util_pair import cons, car, cdr, list, null, print_list
x = cons(1, cons(2, cons(3, cons(4, None))))
print_list(x)
def list_ref(items, n):
if (n == 0):
return car(items)
return list_ref(cdr(items), n - 1)
squares = list([1, 4, 9, 16, 25])
print(list_ref(squares, 3))
def length(items):
if (null(items)):
return 0
return 1 + length(cdr(items))
odds = list([1, 3, 5, 7])
print(length(odds))
def append(list1, list2):
if null(list1):
return list2
def make_rat(n, d):
# return cons(n, d)
g = gcd(n, d)
return cons(int(n / g), int(d / g))
from util_pair import cons, car, cdr, list, print_list x = cons(1, cons(2, cons(3, cons(4, None)))) print_list(x) one_through_four = list([1, 2, 3, 4]) print_list(one_through_four) print(car(one_through_four)) print_list(cdr(one_through_four)) print(car(cdr(one_through_four))) print_list(cons(10, one_through_four)) print_list(cons(5, one_through_four))
def make_rat(n, d):
return cons(n, d)