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# Required Questions #
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# Probably a die-re situation
from operator import add, mul
def reduce(reducer, seq, start):
“””Reduce a sequence under a two-argument function starting from a start value.
>>> def add(x, y):
… return x + y
>>> def mul(x, y):
… return x*y
>>> reduce(add, [1,2,3,4], 0)
>>> reduce(mul, [1,2,3,4], 0)
>>> reduce(mul, [1,2,3,4], 1)
“*** YOUR CODE HERE ***”
def remove_last(x, lst):
“””Create a new list that is identical to lst but with the last
element from the list that is equal to x removed.
>>> remove_last(1,[])
>>> remove_last(1,[1])
>>> remove_last(1,[1,1])
>>> remove_last(1,[2,1])
>>> remove_last(1,[3,1,2])
>>> remove_last(1,[3,1,2,1])
>>> remove_last(5, [3, 5, 2, 5, 11])
[3, 5, 2, 11]
“*** YOUR CODE HERE ***”
def map(f, seq):
Map a function f onto a sequence.
>>> def double(x):
… return x * 2
>>> def square(x):
… return x ** 2
>>> def toLetter(x):
… alpha = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’, ‘h’, ‘i’, ‘j’, ‘k’, ‘l’, ‘m’, ‘n’, ‘o’, ‘p’, ‘q’, ‘r’, ‘s’, ‘t’, ‘u’, ‘v’, ‘w’, ‘x’, ‘y’, ‘z’]
… return alpha[x%26]
>>> map(double, [1,2,3,4])
[2, 4, 6, 8]
>>> map(square, [1, 2, 3, 4, 5, 10])
[1, 4, 9, 16, 25, 100]
>>> map(toLetter, [3, 0, 19, 0])
[‘d’, ‘a’, ‘t’, ‘a’]
“*** YOUR CODE HERE ***”
def hailstone_iterative(n):
“””Print out the hailstone sequence starting at n, and return the
number of elements in the sequence.
>>> a = hailstone_iterative(10)
“*** YOUR CODE HERE ***”
def hailstone_recursive(n):
“””Print out the hailstone sequence starting at n, and return the
number of elements in the sequence.
>>> a = hailstone_recursive(10)
“*** YOUR CODE HERE ***”
def count_change(amount, coins):
“””Returns the number of ways to make change for amount.
>>> coins = [50, 25, 10, 5, 1]
>>> count_change(7, coins)
>>> count_change(100, coins)
>>> coins = [16, 8, 4, 2, 1]
>>> count_change(7, coins)
>>> count_change(10, coins)
>>> count_change(20, coins)
“*** YOUR CODE HERE ***”