# Questions tagged [fastest-algorithm]

Fastest-algorithm competitions are won by the answer with the smallest asymptotic time complexity. For challenges based on actual runtime, use [fastest-code] instead.

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### Minimum Hop Count in Directed Graph based on Conditional Statement [closed]

A directed graph G is given with Vertices V and Edges E, representing train stations and unidirectional train routes respectively. Trains of different train numbers move in between pairs of Vertices ...
277 views

Problem description Vertices $V$ of directed graph $G=(V,E)$ represent gossipping ladies; edge $(u,v) \in E$ signifies that lady $u$ knows of lady $v$ (which does not imply that lady $v$ ...
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### Highest cardinality grouping of contiguous integers with minimum-sum threshold

Challenge Given an array of positive integers and a threshold, the algorithm should output a set of consecutive-element-groupings (subarrays) such that each group/subarray has a sum greater than the ...
202 views

### Compute my Sacred Geometry [closed]

In the tabletop RPG named Pathfinder, there is a feat that characters can take called Sacred Geometry, which allows a character who has it to buff their spells in exchange for doing some math: to use ...
98 views

### Total time to deteriorate all shielded cells [closed]

Problem: We have a two dimensional matrix of positive integer cells. On each turn any non-zero cell with a neighbor (top/bottom/left/right) of zero decreases by 1. We want count to the number of non-...
221 views

### Is this number a palindrome? [closed]

Input A single integer in your language's preferred format, e.g int or an array of digits are all acceptable. Output A truthy or falsely value, depending on ...
3k views

Upside-Down Pyramid Addition is the process of taking a list of numbers and consecutively adding them together until you reach one number. When given the numbers ...
215 views

### Minimum cost of solving the Eni-Puzzle

You're tasked with writing an algorithm to efficiently estimate cost of solving an Eni-Puzzle from a scrambled state as follows: You're given m lists of containing n elements each(representing the ...
308 views

### Buy the most appropriate items

A store is having a big sale. If your price reaches $199 or more, you can reduce it by$100. You can buy each product only once. Here's an example list of products: (in order to simplify, the names of ...
97 views

### determine if the circle is boxed in [closed]

Pretty simple challenge here. Who can make the fastest algorithm (lowest time complexity) to determine whether or not the circle is "boxed in" given the following setup? Input: Your program receives ...
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### Meeting splitter

Introduction Large meetings waste working time. Our aim is to split a large meeting into a number of smaller meetings, so the average number topics that a person discusses is minimized but every ...
286 views

### Fastest way to perform the equivalent of an if-statement in x86 assembly

The task is simple: Create an if-statement from scratch in x86 assembly that runs in as few clock-cycles as possible. Must be x86 assembly. Can't use any of the conditional jump/branch instructions (...
324 views

### Two Dimensional Waterflow problem [closed]

The one dimensional twitter waterflow problem is this: You are given an array that represents a hill in the sense that the ith entry is the height of the ith location of the hill. When it rains, ...
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### 3-inverter with two NOT gates [closed]

Introduction I recently came across an oral exam where the candidates were asked to find a logical circuit than can negate 3 inputs A,B,C using only two NOT gates. ...
354 views

### Find elements in an array computing a given function value

Problem Description Given: a function $f(a, b, c, d, e) = \frac{a \times b}c + \frac de$ an array $x = [x_1, x_2, x_3, x_4, ..., x_n]$ of non-distinct integers a target value $k$ What is the ...
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### Which number is bigger?

Define f(a,b) := a if b=1; a^f(a,b-1) if b>1 (Tetration, where ^ means power) for positive integers ...
212 views

### Find the longest uninterrupted arc in N dimensions

See similar question for 2D case: Find the longest uninterrupted arc The challenge here is to find the longest uninterruped great circle arc around a unit hypersphere in N dimensions, with a random ...
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### Find the longest uninterrupted arc

The challenge here is to find the longest uninterruped arc around a unit circle with a random amount of points distributed in random positions around it. Here is a diagram to assist my explanation: ...
319 views

### Fastest to find the joint

The input is an array (or space-separated string, as you wish), zero-indexed, consisting of one strictly increasing array and one strictly decreasing array (in this order, not other vice versa), each ...
429 views

### Remove entries from array to sort it and maximize sum of elements

This challenge is from an admission test to a closed number cyber security course. Anyway it doesn't have to do with cyber security, it's just to test the students logical and coding skills. Task ...
860 views

### Approximate floating point number with n-digit precision

We have a floating point number r between 0 and 1, and an integer p. Find the fraction of integers with the smallest ...
1k views

### remove duplicates from array [closed]

You have given an array from which we need to remove duplicates. Rules: First or immediate duplicates gets removed first. Array contains natural numbers ...
133 views

### Find the rectangle [closed]

Overview Given a 2 dimensional array of values with a filled in rectangle, find the position and size of the rectangle. Do it in the fewest array accesses as possible. Requirements The ...
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### Total Derangement (Difficulty Level: Hard)

The problem: Write a function which, given a cycle length n and a number of cycles m, where 'm' is within ...
256 views

### Solve a Single Player Tron Game [closed]

Solve a Tron Game Tron is a great game, and if you haven't played it the internet has MANY online versions available. A fun challenge is to try to write an AI that plays Tron, which is normally much ...
115 views

### Sequence avoiding near collision [closed]

Task Find a sequence of all numbers between min and max where every number differs from every other number in the sequence by at least "d" digits. Example of sub-sequence For min = 0, max = 1000 ...
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### Quotient in base 31 numeral system [closed]

You're given two numbers a and b in base 31 numeral system and number k with no more than 10000 decimal digits. It is known that b is divisor of a. The task is to find last k 31-based-digits of ...
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### Digital River (Shortest And Fastest Solution)

This is my first question, so I hope it goes well. Background: It's not the rivers that you might be thinking about. The question revolves around the concept of digital rivers. A digital river is a ...
2k views

### Find the digit occurring the most in a range of prime numbers

Find the digit which occurs the most in a range of prime numbers. Input: Two numbers, p and q, specifying the range; the range ...
193 views

### Num of pyramids possible with given number of bricks [closed]

I encountered this question in an interview and could not figure it out. I believe it has a dynamic programming solution but it eludes me. Given a number of bricks, output the total number of 2d ...
665 views

### Hard Puzzle Game Solver [closed]

There is an app called Hard Puzzle which is a game where there is a red circle, and you have to fill all of the surface area with five smaller white circles it may seen easy, but it's harder than it ...
850 views

### Heaviest increasing subsequence

A subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements. A strictly increasing subsequence is a subsequence ...
223 views

### Add or subtract numbers to find the smallest non-negative integer [closed]

Given a positive integer, n, along with n non-negative integers, write a program or function that prints or returns the smallest ...
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### Number of unique outputs by substituting variables

Given a set of formulas like this: bacb bcab cbba abbc Give an algorithm that finds the number of unique results you can get when each variable is substituted ...
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### Determine sets of associatively equivalent permutations of commutative operations

There are many types of binary operations, which can be categorized by their associative properties and their commutative properties. A binary operation () is ...
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### Fastest way to compute order of magnitude in x86 assembly

The task is simple: write assembly that computes the order of magnitude of an integer using as few clock cycles as possible. Order of magnitude is defined as log10,...
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### Find the longest recurring substring [duplicate]

Given a string of no more than 255 characters, find a function that returns the longest recurring substring. An example would be: aabbacadeauaaabba where the longest recurring sub-string is aabba. ...
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### Find Anagrams in the Dictionary [closed]

This a code challenge. The winner will be the person to provide the most efficient implementation of the solution in terms of algorithmic complexity. Using the dictionary found in '/usr/share/dict' (...
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### A fastest algorithm optimization challenge

This is my first experiment with an asymptotic complexity challenge although I am happy with answers entirely in code as long as they come with an explanation of their time complexity. I have the ...
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### Determine the move in which a LOGO turtle crosses a point that it has already visited [closed]

Situation: A turtle starts at (0, 0) on a cartesian graph. We have a non-empty zero-indexed "moves" list that contains numbers. Each number represents the distance moved. The first number is the ...
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### Same word when missing letters [closed]

Idea From a given word dictionary (containing only plain letters, i.e: no accent or other special chars), with a given fixed word length, find every same when a given number letters are missing. For ...
856 views

### Mr. Moneybag's Money Piles

Mr. Moneybags is a very rich man. He has an assistant Mr. Perfect, who one day, got very mad, and shredded some of Mr. Moneybag’s \$100 bills! Mr. Moneybags decided to punish Mr. Perfect. Mr. ...
686 views

### Racketeer Taxi Driver

The Scenario You are a taxi driver in your city. You picked up a passenger from the airport and he told you the place he'd like to go. To earn more money, you need to drive as much as you can. ...
262 views

### Autoscale complex function

Context: We are working on a complex image drawing program to produce mugs, t-shirts, and so on. Here is an example of such function However, we are facing the following problem: Random generated ...
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### Count the Zeros

For a given n, count the total number of zeros in the decimal representation of the positive integers less than or equal to n. For instance, there are 11 zeros in the decimal representations of the ...
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### Array Merge without Duplicates

I recently saw this Javascript code on StackOverflow for merging two arrays, and removing duplicates: ...