Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Challenges

Post History

81%
+7 −0
Challenges Reduce over the range [1..n]

Task I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of ...

14 answers  ·  posted 2y ago by user‭  ·  last activity 1y ago by gifti‭

#2: Post edited by user avatar user‭ · 2021-08-10T19:41:44Z (over 2 years ago)
Remove blackbox function stuff
  • # Task
  • I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of those functions:
  • $$F(n) = 1 * 2 * \space ... \space * (n-1) * n$$
  • Please note that the operator $ * $ does not necessarily represent multiplication here, but stands for a [commutative](https://en.wikipedia.org/wiki/Commutative_property), [associative](https://en.wikipedia.org/wiki/Associative_property) operator that will be an input to your program/function. This means that $a * b$ is the same as $b * a$, and $a * (b * c)$ is the same as $(a * b) * c$. Its inputs are positive integers, and its outputs are integers.
  • # Rules
  • - $n$ will be a positive integer.
  • - $*$ is a binary function/operator that can be taken in any convenient format, including but not limited to:
  • - A function object
  • - A function pointer
  • - An object with a method with a specific name (e.g. Java's [`BiFunction`](https://docs.oracle.com/javase/8/docs/api/java/util/function/BiFunction.html[]()))
  • - A string that can be evaluated to get a function
  • - $*$ is a blackbox function. That means that you will not be able to examine it to see how it works; all you can do is feed it two positive integers and get an integer back.
  • - The output of your function will be an integer (not necessarily positive).
  • - This is <a class="badge is-tag">code golf</a>, so shortest code in bytes wins!
  • # Testcases
  • ```
  • f | n | F(f, n)
  • Add | 1 | 1
  • Add | 5 | 15
  • Multiply | 1 | 1
  • Multiply | 5 | 120
  • XOR | 1 | 1
  • XOR | 2 | 3
  • XOR | 5 | 1
  • XOR | 10 | 11
  • ```
  • # Task
  • I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of those functions:
  • $$F(n) = 1 * 2 * \space ... \space * (n-1) * n$$
  • Please note that the operator $ * $ does not necessarily represent multiplication here, but stands for a [commutative](https://en.wikipedia.org/wiki/Commutative_property), [associative](https://en.wikipedia.org/wiki/Associative_property) operator that will be an input to your program/function. This means that $a * b$ is the same as $b * a$, and $a * (b * c)$ is the same as $(a * b) * c$. Its inputs are positive integers, and its outputs are integers.
  • # Rules
  • - $n$ will be a positive integer.
  • - $*$ is a binary function/operator that can be taken in any convenient format, including but not limited to:
  • - A function object
  • - A function pointer
  • - An object with a method with a specific name (e.g. Java's [`BiFunction`](https://docs.oracle.com/javase/8/docs/api/java/util/function/BiFunction.html[]()))
  • - A string that can be evaluated to get a function
  • - <s>$*$ is a blackbox function. That means that you will not be able to examine it to see how it works; all you can do is feed it two positive integers and get an integer back.</s>
  • - The output of your function will be an integer (not necessarily positive).
  • - This is <a class="badge is-tag">code golf</a>, so shortest code in bytes wins!
  • # Testcases
  • ```
  • f | n | F(f, n)
  • Add | 1 | 1
  • Add | 5 | 15
  • Multiply | 1 | 1
  • Multiply | 5 | 120
  • XOR | 1 | 1
  • XOR | 2 | 3
  • XOR | 5 | 1
  • XOR | 10 | 11
  • ```
#1: Initial revision by user avatar user‭ · 2021-08-10T14:35:07Z (over 2 years ago)
Reduce over the range [1..n]
# Task

I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of those functions:

$$F(n) = 1 * 2 * \space ... \space * (n-1) * n$$

Please note that the operator $ * $ does not necessarily represent multiplication here, but stands for a [commutative](https://en.wikipedia.org/wiki/Commutative_property), [associative](https://en.wikipedia.org/wiki/Associative_property) operator that will be an input to your program/function. This means that $a * b$ is the same as $b * a$, and $a * (b * c)$ is the same as $(a * b) * c$. Its inputs are positive integers, and its outputs are integers.

# Rules
- $n$ will be a positive integer.
- $*$ is a binary function/operator that can be taken in any convenient format, including but not limited to:
  - A function object
  - A function pointer
  - An object with a method with a specific name (e.g. Java's [`BiFunction`](https://docs.oracle.com/javase/8/docs/api/java/util/function/BiFunction.html[]()))
  - A string that can be evaluated to get a function
- $*$ is a blackbox function. That means that you will not be able to examine it to see how it works; all you can do is feed it two positive integers and get an integer back.
- The output of your function will be an integer (not necessarily positive).
- This is <a class="badge is-tag">code golf</a>, so shortest code in bytes wins!

# Testcases

```
f         | n  | F(f, n)
Add       | 1  | 1
Add       | 5  | 15
Multiply  | 1  | 1
Multiply  | 5  | 120
XOR       | 1  | 1
XOR       | 2  | 3
XOR       | 5  | 1
XOR       | 10 | 11
```