Questions tagged [counting]
For challenges regarding counting the number of occurrences of some characteristic.
130 questions
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Count number of families of sets satisfying a list of criteria
CHALLENGE
This problem has a math background.
For n=1,2,3,4 we want to count the number of families of sets with maximum n elements that satisfy many criteria of the form:
$$\bigoplus_{k\in A,A\in \...
- 357
17
votes
20
answers
2k
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Number of legal positions in 1D go
A 1D go position on a board of size n is a sequence of length n consisting of the numbers0, <...
- 2,518
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21
answers
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7
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12
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821
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Counting constrained permutations
Challenge:
Write a program or function that, given positive integers n, t, b, c, counts permutations of 1..n where:
Exactly t numbers are in their original position
Exactly b numbers are higher than ...
- 79
-1
votes
1
answer
192
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Golomb's self-describing sequence problem [duplicate]
Inspired by this problem.
Golomb's self-describing sequence g(n) is a sequence where any natural number n is repeated within the sequence g(n) times.
Given an input of \$ n \$, output: $$ \left( \sum_{...
- 1
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votes
17
answers
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Count N-Rich Permutations of an Integer Sequence
Given a sequence of integers with length \$L\$ and an integer \$1 \le N \le L\$, an "\$N\$-rich" permutation is one whose the longest strictly increasing contiguous subsequence has length ...
- 1,533
31
votes
50
answers
3k
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Replace 0s In a String With Their Consecutive Counts
Challenge
Given a string of any length which contains only digits from 0 to 9, replace each consecutive run of the digit ...
user113990
28
votes
49
answers
3k
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Count /[^a-z]/ig with /[a-z]/ig
Write a program or function which takes a string of text as input and outputs the number of non-alphabetical characters in it (standard I/O rules apply). A non-alphabetical character is any character ...
- 2,647
10
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1
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Counting overlapping objects
Consider a NxN pixel grid with up to M objects drawn on it, either squares or diamonds:
square
diamond
The objects may overlap, so recognition is hard. The task is to give the minimal possible ...
16
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14
answers
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Count count count
Description
You have a list of integers and start counting from the first term to the next and continue from that to the next and so on..
How many times have you counted?
For example given [ 2, 5, 3, ...
- 11k
34
votes
30
answers
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Converge to a number
Your challenge is to, given a positive integer n, count up to each digit of it, giving the effect of converging on it.
Basically, count up to the first digit of n by its place value (\$⌊\log_{10}\left(...
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22
votes
36
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Return all letter counts as an integer
Definition
Given some string return an integer whose digits are the number ocurrences of a-z (case insensitive, in alphabetical order) in that string. Any character with 0 instances is skipped. ...
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votes
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Counting and so on
Content
You count numbers every day (I think), and most of you know how to count properly, the one next to 1 is 2, and the next ...
- 1,807
15
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12
answers
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How many Sets are there?
This is similar in concept to this challenge, but that is pretty restrictive on input and output and I think opening up these restrictions would lead to a completely different set of solutions that ...
- 1,533
33
votes
55
answers
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Replace all items with their counts
Task:
Given an array of numbers as input (you can choose what subset, such as integers or natural numbers), replace all items with the number of times they appear within the array. As an example, <...
- 19.3k
27
votes
19
answers
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Possible periods of input
Background:
Take this input as an example:
1 1 2 1 1 2 1 3 1 3
If you look only at the first few digits, between 1 1 2 and <...
- 19.3k
13
votes
10
answers
1k
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Autogrammatic pairs
For today's task, we have two programs, P and Q, both in the same language. Each of them receives a single-character input.
If P receives character K, P says how many times K appeared in Q. (You can ...
- 3,939
19
votes
13
answers
1k
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Count strictly overlapping substrings
Given two strings a and b, count how many times b occurs as a substring in ...
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23
votes
2
answers
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Eye test - How many squares are in this picture?
The picture:
Sick of the same old grid where the answer is simply a square pyramidal number?
Accept the challenge and write a program that given a positive integer \$n\$ counts how many squares are in ...
- 2,463
3
votes
2
answers
667
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Remove duplicates from list and order it by count? (python 3)
How do I remove all duplicates from list and order it based on count?
...
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13
votes
6
answers
512
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Number of solutions to a binary weight equation
We define \$a(n)\$ as the 1-indexed position of \$n\$ in the sequence of positive integers with the same binary weight, i.e. the same number of 1's in their binary representation. This is A263017.
...
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28
votes
9
answers
1k
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Analyze the flow
On a toroidal square grid (you can wrap around) where each cell indicates one direction (^ > ...
- 2,463
20
votes
1
answer
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Acyclic orientations of an n-dimensional cube
The goal of this challenge is to check and extend the OEIS sequence A334248: Number of distinct acyclic orientations of the edges of an n-dimensional cube.
Take an n-dimensional cube (if n=1, this is ...
- 309
32
votes
6
answers
2k
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Slash the matrix
You are given a matrix of forward and back slashes, for instance:
//\\
\//\
//\/
A slash cuts along the diagonal of its cell corner-to-corner, splitting it in ...
- 15.6k
5
votes
19
answers
475
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How many spaces are there? [duplicate]
Your task is to input a string, and output the number of spaces in the string.
This is code-golf, so least number of bytes win. Your
Test Cases
Double quotes are not part of the test cases.
...
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34
votes
28
answers
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Count rook moves 1D
Given a position with a row of rooks and/or empty spaces, output how many different rook moves are possible. A rook can move left or right to an empty space, but not to one that requires passing over ...
- 150k
3
votes
1
answer
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Black and white shirt 2
This is a more complicated version of this puzzle. The premise is the same but a few rules differ in a few key places, making for a more complex problem.
Assume I have some number of black shirts and ...
- 299
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votes
43
answers
5k
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Character Frequency in a String [duplicate]
Given a string of printable ASCII, output the frequency of each character in that string.
The Challenge
Input is given as a string of printable ASCII characters (decimal ...
- 11.5k
29
votes
23
answers
6k
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A scene of Jimmy diversity
As you probably know, there have been multiple lovely Jimmy challenges recently popping up. In these challenges, you were challenged with our beloved friend's acrobatics skills. Now we've got a ...
- 2,578
51
votes
34
answers
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Covering a Skyline with brush strokes
Given a non-negative integer skyline height list, answer how many uninterrupted 1-unit-high horizontal brush strokes are needed to cover it.
[1,3,2,1,2,1,5,3,3,4,2]...
- 31.8k
20
votes
32
answers
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How fast am I vrooooming?
Introduction
My car speedometer was hacked! Instead of showing me how fast i'm driving, it just shows: "Vroooom!" Please help me know how fast i'm going.
Challenge
Take a string as input, ...
- 941
21
votes
5
answers
507
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Count cyclically self-describing lists
Cyclically self-describing lists
A list \$L\$ of positive integers is cyclically self-describing, if the following conditions hold.
\$L\$ is nonempty.
The first and last elements of \$L\$ are ...
- 43.2k
8
votes
14
answers
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Recursively count lines of code, excluding empty lines and comments
Requirement: Write a program (in any language) that counts the number of lines of code in files matching *.sh in the directory tree starting from the directory that ...
- 207
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votes
20
answers
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Longest Repeating Subsequence of a Single Digit
Challenge:
Given a positive integer, output the longest single-digit subsequence that occurs at least twice, AND has boundaries of another digit (or the start/end of the integer).
An example:
Input: <...
- 136k
11
votes
5
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Saddle points in a matrix
A matrix can be thought of as the altitudes of a surface in 3D space.
Consider the 8 neighbours (orthogonal and diagonal) of a cell as a cyclic sequence in clockwise (or anticlockwise) order. Some ...
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20
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How long is this string?
It's strange this question hasn't been asked yet, so here it is:
Calculate the length of a string given through STDIN
Rules
As said, your string will be given through STDIN, not via command line ...
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16
votes
10
answers
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Assign Airliner Seats
Inspired by last week's APL lesson.
Given an uppercase 2D seat map and a 1D list of customers, return the seat map and the customer list but modified as follows (to indicate occupied seats and seated ...
- 31.8k
34
votes
22
answers
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Alphabet Histogram
Given an input sentence consisting of one or more words [a-z]+ and zero or more spaces , output an ASCII-art histogram (bar ...
- 43.7k
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votes
21
answers
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Count the Matchsticks
Most people here are familiar with seven segment displays, which are also used in matchstick puzzles. Below are the digits 0 through ...
- 43.7k
3
votes
2
answers
116
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Count stacking sequences [duplicate]
Given a list of stack heights, calculate the number of ways those heights could have been arrived at by stacking blocks one at a time. Shortest code wins.
Test cases:
...
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27
votes
29
answers
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Count edits accounting for grace period
When you edit a post on SE, any further edits within a 5-minute grace period are merged into it. Given a list of times you edit a post, count the edits not in a grace period.
Say you edit at minutes <...
- 150k
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votes
24
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Plus Primes vs Minus Primes
Most of us know...
that all primes p>3 are of the form
But, how many are the Plus Primes (6n+1) and how many are the ...
user73398
16
votes
11
answers
936
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Sequence Without Sevens [duplicate]
This challenge is based on a drinking game. I advise against alcohol consumption while programming.
In this game, the players count up in turns: the first player says ...
- 1,241
24
votes
28
answers
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Count forth and back then double up
Let's count...
Count up to 2 and back to 1
Count up to 4 and back to 1
Count up to 6 and back to 1
... ok you got it...
put all these together and you'll get the following sequence
...
user73398
26
votes
10
answers
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Number Lockers!
Given a positive integer < 100 (from 1 to 99, including 1 and 99), output that many lockers.
A locker is defined as the following:
...
- 6,954
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19
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How much reputation does a steam user have? [closed]
Introduction
For those not familiar with steam - or at least this particular aspect:
Often on peoples' profiles, people leave comments saying either "+rep _____" or "-rep _____". These are an ...
- 350
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11
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Count how many months are having a full 31 days by counting knuckles
How many of you that still use your own knuckle to determine whether a month is having a full 31 days or less?
You job is to write a program to count how many months, in a month range, are having a ...
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votes
1
answer
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Count # of Cookie Chocolate Chips
Note: this is my first post here.
The Challenge
The challenge is to count the number of chocolate chips in a cookie. A cookie in this case is a circle with dots (the chips) in it. Given any square ...
- 81
36
votes
68
answers
5k
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GET your dubs together
On 4chan, a popular game is get. Every post on the site gets a sequential post ID. Since you can't influence or determine them, people try to guess (at least a part of) their own post number, usually ...
- 1,405
19
votes
8
answers
4k
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How Many Holes?
Challenge
Given a graphical input of a shape, determine how many holes there are in it.
Not Duplicate
This question was marked as a possible duplicate of Count Islands. I believe this challenge is ...
- 42.8k