Is a linked list ordered from least to greatest?
def ordered(s):
"""Is Link s ordered?
>>> ordered(Link(1, Link(3, Link(4))))
True
>>> ordered(Link(1, Link(4, Link(3))))
False
>>> ordered(Link(1, Link(-3, Link(4))))
False
"""
Is a linked list ordered from least to greatest?
def ordered(s, key=lambda x: x):
"""Is Link s ordered?
>>> ordered(Link(1, Link(3, Link(4))))
True
>>> ordered(Link(1, Link(4, Link(3))))
False
>>> ordered(Link(1, Link(-3, Link(4))))
False
"""
if s is Link.empty or s.rest is Link.empty:
return True
elif s.first > s.rest.first:
return False
else:
return ordered(s.rest)
Is it ordered when a key function is applied, like abs?
def ordered(s, key=lambda x: x):
"""Is Link s ordered?
>>> ordered(Link(1, Link(3, Link(4))))
True
>>> ordered(Link(1, Link(4, Link(3))))
False
>>> ordered(Link(1, Link(-3, Link(4))))
False
>>> ordered(Link(1, Link(-3, Link(4))), key=abs)
True
>>> ordered(Link(-4, Link(-1, Link(3))))
True
>>> ordered(Link(-4, Link(-1, Link(3))), key=abs)
False
"""
Is it ordered when a key function is applied, like abs?
def ordered(s, key=lambda x: x):
"""Is Link s ordered?
>>> ordered(Link(1, Link(3, Link(4))))
True
>>> ordered(Link(1, Link(4, Link(3))))
False
>>> ordered(Link(1, Link(-3, Link(4))))
False
>>> ordered(Link(1, Link(-3, Link(4))), key=abs)
True
>>> ordered(Link(-4, Link(-1, Link(3))))
True
>>> ordered(Link(-4, Link(-1, Link(3))), key=abs)
False
"""
if s is Link.empty or s.rest is Link.empty:
return True
elif key(s.first) > key(s.rest.first):
return False
else:
return ordered(s.rest, key)
Create a sorted Link containing all the elements of two sorted Links.
+ =
def merge(s, t):
"""Return a sorted Link containing the elements of sorted s & t.
>>> a = Link(1, Link(5))
>>> b = Link(1, Link(4))
>>> merge(a, b)
Link(1, Link(1, Link(4, Link(5))))
>>> a
Link(1, Link(5))
>>> b
Link(1, Link(4))
"""
Create a sorted Link containing all the elements of two sorted Links.
+ =
def merge(s, t):
"""Return a sorted Link containing the elements of sorted s & t.
>>> a = Link(1, Link(5))
>>> b = Link(1, Link(4))
>>> merge(a, b)
Link(1, Link(1, Link(4, Link(5))))
>>> a
Link(1, Link(5))
>>> b
Link(1, Link(4))
"""
if s is Link.empty:
return t
elif t is Link.empty:
return s
elif s.first <= t.first:
return Link(s.first, merge(s.rest, t))
else:
return Link(t.first, merge(s, t.rest))
This time, do it without creating any new Link objects.
def merge_in_place(s, t):
"""Return a sorted Link containing the elements of sorted s & t.
>>> a = Link(1, Link(5))
>>> b = Link(1, Link(4))
>>> merge_in_place(a, b)
Link(1, Link(1, Link(4, Link(5))))
>>> a
Link(1, Link(1, Link(4, Link(5))))
>>> b
Link(1, Link(4, Link(5)))
"""
This time, do it without creating any new Link objects.
def merge_in_place(s, t):
"""Return a sorted Link containing the elements of sorted s & t.
>>> a = Link(1, Link(5))
>>> b = Link(1, Link(4))
>>> merge_in_place(a, b)
Link(1, Link(1, Link(4, Link(5))))
>>> a
Link(1, Link(1, Link(4, Link(5))))
>>> b
Link(1, Link(4, Link(5)))
"""
if s is Link.empty:
return t
elif t is Link.empty:
return s
elif s.first <= t.first:
s.rest = merge_in_place(s.rest, t)
return s
else:
t.rest = merge_in_place(s, t.rest)
return t
What are the indices of all elements in a list that have the smallest absolute value?
[-4, -3, -2, 3, 2, 4] → [2, 4]
0 1 2 3 4 5
[ 1, 2, 3, 4, 5, 6] → [0]
0 1 2 3 4 5
def min_abs_indices(s):
"""Indices of all elements in list s that have the smallest absolute value.
>>> min_abs_indices([-4, -3, -2, 3, 2, 4])
[2, 4]
>>> min_abs_indices([1, 2, 3, 4, 5])
[0]
"""
What are the indices of all elements in a list that have the smallest absolute value?
[-4, -3, -2, 3, 2, 4] → [2, 4]
0 1 2 3 4 5
[ 1, 2, 3, 4, 5, 6] → [0]
0 1 2 3 4 5
def min_abs_indices(s):
"""Indices of all elements in list s that have the smallest absolute value.
>>> min_abs_indices([-4, -3, -2, 3, 2, 4])
[2, 4]
>>> min_abs_indices([1, 2, 3, 4, 5])
[0]
"""
min_abs = min(map(abs, s))
return list(filter(lambda i: abs(s[i]) == min_abs, range(len(s))))
# OR
return [i for i in range(len(s)) if abs(s[i]) == min_abs]
What's the largest sum of two adjacent elements in a list? (Assume length > 1)
[-4, -3, -2, 3, 2, 4] → 6
-7 -5 1 5 6
[-4, 3, -2, -3, 2, -4] → 1
-1 1 -5 -1 -2
def largest_adj_sum(s):
"""Largest sum of two adjacent elements in a list s.
>>> largest_adj_sum([-4, -3, -2, 3, 2, 4])
6
>>> largest_adj_sum([-4, 3, -2, -3, 2, -4])
1
"""
What's the largest sum of two adjacent elements in a list? (Assume length > 1)
[-4, -3, -2, 3, 2, 4] → 6
-7 -5 1 5 6
[-4, 3, -2, -3, 2, -4] → 1
-1 1 -5 -1 -2
def largest_adj_sum(s):
"""Largest sum of two adjacent elements in a list s.
>>> largest_adj_sum([-4, -3, -2, 3, 2, 4])
6
>>> largest_adj_sum([-4, 3, -2, -3, 2, -4])
1
"""
return max([x + y for x, y in zip(s[:-1], s[1:])])
# OR
return max([s[i] + s[i + 1] for i in range(len(s) - 1)])
# OR
return max(map(lambda i: s[i] + s[i + 1], range(len(s) - 1)))