Structure and Interpretation of Computer Programs (SICP) is a classic textbook for learning how to program. The language used in the book is Scheme, a dialect of Lisp.
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votes
1answer
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SICP - exercise 1.11 - tree recursion
From SICP
Exercise 1.11: A function \$f\$ is defined by the rule that:
\$f(n) = n\$ if \$n < 3\$, and
\$f(n) = f(n-1)+2f(n-2)+3f(n-3)\$ if \$n >= 3\$.
Write a procedure ...
3
votes
1answer
36 views
Square root calculation in Scheme (SICP Exercise 1.7)
I have done exercise 1.7 in SICP (calculate square root precision when change in guesses is under a certain value), but I am calling the change-in-precision function twice in each iteration, which ...
2
votes
1answer
45 views
SICP exercise 1.3 - sum of squares of two largest of three numbers
From SICP
Exercise 1.3: Define a procedure that takes three numbers as arguments and returns the sum of the squares of the two larger numbers.
Square is:
...
4
votes
1answer
49 views
SICP - exercise 2.69 - generate a huffman tree from a set of ordered leaves
From SICP
Exercise 2.69: The following procedure takes as its argument a list of
symbol-frequency pairs (where no symbol appears in more than one pair)
and generates a Huffman encoding tree ...
3
votes
1answer
55 views
SICP exercise 2.28 - counting leaves in a tree (recursive process)
From SICP
Exercise 2.28: Write a procedure fringe that takes as argument a tree
(represented as a list) and returns a list whose elements are all the
leaves of the tree arranged in ...
2
votes
2answers
55 views
SICP - exercise 2.27 - reversing elements of a list and sublists
From SICP
Exercise 2.27: Modify your deep-reverse procedure of Exercise 2.18 to produce a deep-deep-reverse procedure that takes a list as argument and returns as its value the list with its ...
1
vote
1answer
44 views
SICP - exercise 2.5 - representing pairs of nonnegative integers using only numbers and arithmetic operations
From SICP
Exercise 2.5: Show that we can represent pairs of nonnegative integers using only numbers and arithmetic operations if we represent the pair a and b as the integer that is the product ...
2
votes
1answer
21 views
Replacing elements from a list and its sublists - part II
This is sort of a follow-up to
Replacing elements from a list and its sublists
but now there are arbitrary numbers of words that would be replaced stored in a list.
Now write substitute2 that takes ...
1
vote
2answers
38 views
SICP - exercise 2.20 - same-parity
Exercise 2.20.
The procedures +, *, and list take arbitrary numbers of arguments. One way to define such procedures is to use define with dotted-tail notation. In a procedure
definition, a ...
3
votes
1answer
43 views
Reversing a list without (append)
I would like to reverse a list using cdr, car and cons. Since lists in lisp are asymmetrical (can only insert at the beginning), I am interested on how one would write a procedure to do that without ...
3
votes
1answer
44 views
Replacing elements from a list and its sublists
Write a procedure substitute that takes three arguments: a list, an old word, and a new word. It should return a copy of the list, but with every occurrence of the old word replaced by the new word, ...
5
votes
1answer
53 views
Finding next perfect number - brute force
A “perfect number” is defined as a number equal to the sum of all its factors less than itself. For example, the first perfect number is 6, because its factors are 1, 2, 3, and 6, and 1+2+3=6. The ...
4
votes
2answers
75 views
Squaring a tree in Clojure
I am working on Problem 2.30 from Structure and Interpretation of Computer Programs. I book is in scheme, but I am doing the exercises in Clojure.
The problem is to write code that takes a tree of ...
3
votes
1answer
49 views
Replacing words from a sentence
I am extremely new at scheme and I am doing this problem from here:
Write a procedure switch that takes a sentence as its argument and
returns a sentence in which every instance of the words I ...
5
votes
3answers
350 views
Recursive and iterative approach for mergesort
Problem:
Question 8: *
Mergesort is a type of sorting algorithm. It follows a naturally
recursive procedure:
Break the input list into equally-sized halves Recursively sort both ...
-1
votes
2answers
176 views
Filter a list with given predicate - python [closed]
For the following question, the function
• should mutate the original list
• should NOT create any new lists
• should NOT return anything
Function that do not create new lists ...
2
votes
5answers
3k views
Shift elements left by n indices in a list
For the following question, the function
• should mutate the original list
• should NOT create any new lists
• should NOT return anything
Functions that do not create new lists ...
0
votes
1answer
103 views
Interval multiplication - faster version
For the below given problem from this assignment:
Q4. In passing, Ben also cryptically comments, "By testing the signs of the endpoints of the intervals, it is possible to break ...
1
vote
1answer
162 views
Is there something wrong with my remove-duplicates implementation in Scheme?
For an assignment I handed in this code to remove duplicates from a stream.
...
3
votes
1answer
65 views
SICP Exercise 1.3: Sum of squares of two largest numbers out of three, Prolog Version
The exercise 1.3 of the book Structure and Interpretation of Computer Programs asks the following:
Exercise 1.3. Define a procedure that takes three numbers as arguments and returns the sum of ...
3
votes
1answer
47 views
SICP Exercise 1.3: Sum of squares of two largest numbers out of three, Rust Version
The exercise 1.3 of the book Structure and Interpretation of Computer Programs asks the following:
Exercise 1.3. Define a procedure that takes three numbers as arguments and returns the sum of ...
5
votes
1answer
127 views
SICP Exercise 1.3: Sum of squares of two largest numbers out of three, Haskell Version
The exercise 1.3 of the book Structure and Interpretation of Computer Programs asks the following:
Exercise 1.3. Define a procedure that takes three numbers as arguments and returns the sum of ...
5
votes
3answers
307 views
SICP Exercise 1.3: Sum of squares of two largest numbers out of three
The exercise 1.3 of the book Structure and Interpretation of Computer Programs asks the following:
Exercise 1.3. Define a procedure that takes three numbers as arguments and returns the sum of ...
3
votes
1answer
78 views
SICP streams in C++
To brush up on my C++ chops, I've implemented a toy version of "SICP Streams", which behave like lists with one twist: the first element of the list is always available, the rest of the list is stored ...
4
votes
0answers
110 views
Building Data abstraction and ADT for rectangle using “objects”
For the below given exercise:
Exercise 7: Abstracting Rectangles
Implement a representation for rectangles in a plane. (Hint: You may want to make use of your procedures from exercise 5). ...
4
votes
1answer
89 views
Encapsulated state in clojure
While going through SICP and trying to implement the code in clojure, I've found that while I can get the code in chapter 3 to work, it seems to go against Clojure idioms, but I can't quite imagine ...
3
votes
2answers
99 views
This snippet of scheme calculates a value in pascal's triangle
I'm working through SICP and have implemented exercise 1.11 (Pascal's Triangle). What I'm curious about here is performance considerations by defining functions within the main function. I would ...
7
votes
2answers
398 views
My first accumulators
Notes
I'm working my way through SICP, and as I got very confused by the section on folds, I decided to try to implement foldr in scheme and javascript to understand how it works differently with ...
1
vote
0answers
155 views
SICP ex. 2.42 “eight queens puzzle”
The problem can be found online here.
In short, we're given the following function definition, that will recursively generate all the possible solutions for the "eight-queen-problem".
...
7
votes
2answers
166 views
Write a procedure stream-limit that finds
From SICP:
Exercise 3.64. Write a procedure
stream-limit that takes as arguments a
stream and a number (the tolerance).
It should examine the stream until it
finds two successive elements ...
1
vote
0answers
155 views
Write a definition of a semaphore in terms of test-and-set! operations
From SICP:
Exercise 3.47. A semaphore (of size
n) is a generalization of a mutex.
Like a mutex, a semaphore supports
acquire and release operations, but it
is more general in that up to n
...
1
vote
0answers
167 views
Write a definition of a semaphore in terms of mutexes
From SICP:
Exercise 3.47. A semaphore (of size
n) is a generalization of a mutex.
Like a mutex, a semaphore supports
acquire and release operations, but it
is more general in that up to n
...
3
votes
0answers
148 views
Representing a queue as a procedure with local state
From SICP:
Exercise 3.22. Instead of
representing a queue as a pair of
pointers, we can build a queue as a
procedure with local state. The local
state will consist of pointers to the
...
4
votes
1answer
273 views
Examine a list for cycles
From SICP:
Exercise 3.18. Write a procedure that
examines a list and determines whether
it contains a cycle, that is, whether
a program that tried to find the end
of the list by taking ...
1
vote
0answers
434 views
Correctly count the number of pairs in an irregular list structure
From SICP:
For background, here is exercise 3.16:
Exercise 3.16
Ben Bitdiddle decides
to write a procedure to count the
number of pairs in any list structure.
...
1
vote
1answer
277 views
Order of evaluation of function arguments
From SICP:
Exercise 3.8
When we defined the
evaluation model in section 1.1.3, we
said that the first step in evaluating
an expression is to evaluate its
subexpressions. But we never ...
1
vote
0answers
153 views
Coercion of arguments using successive raising
From SICP:
Exercise 2.84
Using the raise
operation of exercise 2.83, modify the
apply-generic procedure so that it
coerces its arguments to have the same
type by the method of ...
1
vote
0answers
333 views
Coercion with multiple arguments
From SICP:
Exercise 2.82
Show how to generalize
apply-generic to handle coercion in
the general case of multiple
arguments. One strategy is to attempt
to coerce all the arguments to ...
2
votes
1answer
728 views
Huffman encoding successive-merge function
From SICP:
Exercise 2.69. The following
procedure takes as its argument a list
of symbol-frequency pairs (where no
symbol appears in more than one pair)
and generates a Huffman encoding ...
1
vote
1answer
814 views
Encode-symbol for Huffman tree
From the text:
Exercise 2.68. The encode procedure
takes as arguments a message and a
tree and produces the list of bits
that gives the encoded message.
...
2
votes
1answer
337 views
Search on a binary tree
From SICP:
Exercise 2.66. Implement the lookup
procedure for the case where the set
of records is structured as a binary
tree, ordered by the numerical values
of the keys.
I wrote the ...
2
votes
0answers
935 views
Union-set intersection-set for a binary-tree implementation of sets
From SICP:
Exercise 2.65
Use the results of
exercises 2.63 and 2.64 to give (n)
implementations of union-set and
intersection-set for sets implemented
as (balanced) binary trees.41
...
1
vote
1answer
314 views
Adjoin-set for an ordered set representation
From SICP:
Exercise 2.61
Give an implementation
of adjoin-set using the ordered
representation. By analogy with
element-of-set? show how to take
advantage of the ordering to produce a
...
4
votes
1answer
182 views
Set representation allowing duplicates
From SICP:
Exercise 2.60. We specified that a
set would be represented as a list
with no duplicates. Now suppose we
allow duplicates. For instance, the
set {1,2,3} could be represented as
...
3
votes
0answers
388 views
Standard Algebraic Derivative Calculator
I had some difficulty with this problem, so I'm sure there is a better way. Here is the question from SICP:
Exercise 2.58
Suppose we want to
modify the differentiation program so
that it ...
3
votes
1answer
275 views
Extend sums and products functions
Exercise 2.57. Extend the
differentiation program to handle sums
and products of arbitrary numbers of
(two or more) terms. Then the last
example above could be expressed as
...
0
votes
1answer
122 views
Extending basic differentiator to handle more kinds of expressions
Exercise 2.56. Show how to extend the
basic differentiator to handle more
kinds of expressions. For instance,
implement the differentiation rule
by adding a new clause to the deriv
...
2
votes
1answer
733 views
equal? predicate for lists
Exercise 2.54
Two lists are said to
be equal? if they contain equal
elements arranged in the same order.
For example,
...
1
vote
1answer
290 views
Adding, subtracting, and multiplying a vector by a scalar
Exercise 2.46. A two-dimensional
vector v running from the origin to a
point can be represented as a pair
consisting of an x-coordinate and a
y-coordinate. Implement a data
abstraction ...
2
votes
1answer
179 views
Writing a general purpose “split” function (for SICP's imaginary language)
From SICP 2.2.4:
The textbook has already defined a function (right-split ...) as follows:
...
