Questions tagged [restricted-time]

For challenges with a restriction on the amount of time a submission is allowed to use.

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15
votes
10answers
2k views

When does hh:mm = mm.ss?

Let's begin with a thought experiment. You have a clock and a timer, in which you start the timer when the clock shows exactly hh:mm.00. Clock: The clock employs ...
10
votes
4answers
317 views

Holey Knight's Tour

Given a rectangular board of cells with some number of holes in it, determine whether it is possible to complete a "holey knight's tour" (That is, a path that visits every non-hole cell exactly once ...
19
votes
2answers
323 views

Exactly N in a line

Given a number N from 2 to 8, place any nonzero number of queens on a grid of any size so that every queen has exactly N queens (counting itself) in each of its row, column, and each diagonal. This ...
10
votes
2answers
450 views

Are these two DFAs equivalent?

Two Deterministic Finite Automata or DFAs can be checked to see if they accept same set of strings in polynomial time. See section 3.3 of this for a long list of methods and this SO question/answer ...
2
votes
5answers
170 views

Shift the digits [closed]

Here, x (supplied as input) and n (the result of your computation) are both positive integers. n * x = n shifted. Find n. Here's an example of shifting: ...
5
votes
3answers
259 views

Choose 3 strings and output the exact minimum Hamming distance between any pair

Consider \$3\$ binary strings of length \$n\$ chosen independently and uniformly at random. We are interested in computing the exact expected minimum Hamming distance between any pair. The Hamming ...
19
votes
2answers
568 views

Counting creatures on a hexagonal tiling

This challenge will have you count "creatures" in the tile game Palago. A creature is any closed shape that can be formed by Palago tiles of matching colour in a hexagonal grid. The game Palago ...
6
votes
4answers
461 views

Find X,Y,Z coordinates from index

Introduction I began studying the Collatz Conjecture And noticed these patterns; 0,1,2,2,3,3...A055086, and 0,1,2,0,3,1...A082375, in the numbers that go to 1 in one odd step, 5,10,20,21,40,42......
-5
votes
5answers
127 views

Report divisibility with arithmetic integer operations only [closed]

Given two numbers, the first is greater than the second, check whether the first number is divisible by the second without a remainder. If divisible, answer "yes"(...
-2
votes
4answers
1k views

Output first \$n\$ digits of \$\pi^{1/\pi}\$

This challenge is to produce the shortest code for the constant \$\pi^{1/\pi}\$. Your code must output the first \$n\$ consecutive digits of \$\pi^{1/\pi}\$, where \$n\$ is given in the input. ...
11
votes
6answers
1k views

Which really big number is bigger?

This question is tricky (and in particular harder than Which big number is bigger?), for those who like more challenging puzzles. Input Integers a1, a2, a3, a4, a5, b1, b2, b3, b4, b5 each in the ...
8
votes
14answers
752 views

Next number with k fives

Challenge: Your program will take two integers n and k as input, and output the smallest integer greater than (but not equal to)...
17
votes
3answers
910 views

Plight of the Concorde

Background The traveling salesman problem (TSP) asks for the shortest circuit that visits a given collection of cities. For the purposes of this question, the cities will be points in the plane and ...
23
votes
23answers
3k views

Encode - Shuffle - Decode

Challenge Your task is to encode an integer as a string of ASCII characters, then successfully decode it after said string has been randomly shuffled. You will write two programs/functions, which ...
8
votes
0answers
338 views

The N Queens Problem, but with Fairy Chess Pieces

Fairy Chess is a sort of generalized chess that allows unconventional pieces. The eight queens puzzle is a classic problem where you have to put 8 queens on a chess board such that no two queens ...
7
votes
2answers
1k views

Solve a Rubik's Cube

Your challenge is to write a program to solve a 3x3x3 Rubik's Cube. This challenge is based on this one from 2013, rewritten to adhere to current community standards, and reposted with the original ...
9
votes
6answers
669 views

Output all distinct permutations of a vector

Challenge: Output all distinct permutations of a, potentially long, list of positive integers. You may assume that the vector has less than 1,000 numbers when testing, but the process should in ...
19
votes
7answers
1k views

Number of distinct non-empty subsequences of binary expansion

A subsequence is any sequence that you can get from another by deleting any amount of characters. The distinct non-empty subsequences of 100 are ...
48
votes
13answers
7k views

Extreme Fibonacci

There have been a billion iterations of Fibonacci challenges on this website, so lets spice things up with a Fibonacci challenge of a billion iterations! Your challenge is to output the first 1000 ...
17
votes
5answers
1k views

Fastest tweetable integer factorizer

The task is to find a non-trivial factor of a composite number. Write code that finds a non-trivial factor of a composite number as quickly as possible subject to your code being no more than 140 ...
13
votes
4answers
1k views

Square root a number

The task is as follows: Given a positive integer x and a prime n > x, output the smallest positive integer ...
21
votes
9answers
4k views

Compute the inverse of an integer modulo 100000000003

The task is the following. Given an integer x (such that x modulo 100000000003 is not equal ...
9
votes
3answers
519 views

Find a number which generates all the integers mod q

Consider the integers modulo q where q is prime, a generator is any integer 1 < x < q ...
16
votes
2answers
339 views

Output a primitive element for each field size

A primitive element of a finite field is a generator of the multiplicative group of the field. In other words, alpha in F(q) is ...
23
votes
6answers
1k views

Fraction to exact decimal

Write a program or function that given two integers a, b outputs a string containing a decimal number representing the fraction a/b exactly. If a/b is integer, simply output the value, without a ...
21
votes
9answers
1k views

Calculating Collatz Cousins

Define the function f(n) for a positive integer n as follows: n / 2, if n is even 3 * n + 1, if n is odd If you repeatedly apply this function to any n greater than 0, the result always seems to ...
32
votes
3answers
3k views

Area of a Self-Intersecting Polygon

Consider a potentially self-intersecting polygon, defined by a list of vertices in 2D space. E.g. ...
38
votes
3answers
23k views

Solve Rubik's cube

Write the shortest program that solves Rubik's cube (3*3*3) within a reasonable amount of time and moves (say, max. 5 seconds on your machine and less than 1000 moves). The input is in the format: <...
22
votes
28answers
4k views

Last non-zero digit of n!

Given an integer 1 ≤ N ≤ 1,000,000 as input, output the last non-zero digit of N!, where ! is the factorial (the product of all numbers from 1 to N, inclusive). This is OEIS sequence A008904. Your ...