Category "algorithm"

Working with small probabilities, via logs

Source: Google Code Jam. https://code.google.com/codejam/contest/10224486/dashboard#s=a&a=1 We're asked to calculate Prob(K successes from N trials) where

Largest Triple Products without using sort?

I implemented the Largest Triple Products algorithm, but I use sort which makes my time complexity O(nlogn). Is there a way to implement it without a temporary

Reasons for using a Bag in Java

I am currently studying about Algorithms & Data Structures and while I was reading over the Book of Algorithms 4th edition, I discovered the Bag data-struct

Extract the century of a date from a string

My task is to output the current century of a given date. The date can be represented as a string; for example, 19.03.2022. How can I retrieve the year and cent

Understanding the Big O for squaring elements in an array

I was working on a problem where you have to square the numbers in a sorted array on leetcode. Here is the original problem Given an array of integers A sor

How to approach this Dynamic Programming Meal Plan Problem?

I came across this problem in a practice interview. I don't want a direct answer, just some help with the intuition of the problem, both your brute force thinki

Is there a known algorithm for finding which K elements out of N elements have a sum that is closest to a whole number?

As a small example, say I have N=6 elements { 0.03, 0.25000039, 1.391, 500.1, 0.5000001, 1.75001 } and K=3 then the combination { 0.25000039, 0.5000001, 0.

count words in a string without using split

I have a problem on which I am working where I need to count the number of words in a string without using the split() function in Python. I thought of an appro

how to calculate XOR (dyadic) convolution with time complexity O(n log n)

“⊕” is the bitwise XOR operation. I think Karatsuba’s algorithm may be used to solve the problem, but when I try to use XOR instead of

Java: How to implement wildcard matching?

I'm researching on how to find k values in the BST that are closest to the target, and came across the following implementation with the rules: '?' Matches

How to generate the worst case for disjoint set with only path compression?

A disjoint set with only path compression implemented is like this: // In cpp. int Find(int x) { return f[x] == x ? x : f[x] = Find(f[x]); } int Union(int a, i

Amazon interview: Min stack

I recently had my Amazon interview for SDE. I was asked to design a stack which does push, pop and min in O(1). I got the logic and implemented the push of the

How to reduce the time complexity of this algorithm?

I provide two data structures, cart_info and map_case, and get the result real_combinationby the algorithm. This algorithm is implemented in python import itert

Finding the shortest path with only passing specific edge less or equal to one time in Graph

Given a undirected graph that it has ordinary edges and specific edges, our goal is to find the sum of the shortest path's weight between two vertices(start ve

Algorithm to find counterfeit coin amongst n coins

So this is the classic problem of finding a counterfeit coin among a set of coins using only a weighing balance. For completeness, here is one example of such a

Count of combinations with repetitions

I have a very inefficient way of counting the combinations of N/2 items from an array of size N. What I do is sort the array to begin with and then loop through

Convert camelCase to snakeCase

I have a dictionary something like this: { 'firstName': 'abc', 'lastName': 'xyz', 'favoriteMovies': ['Star Wars', 'The lone ranger'], 'favo

Does the size of the prime number in Shamir's Secret Sharing affect the security of the sharding?

I've been working on an implementation of Shamir's Secret Sharing, and was wondering if the prime number selected will impact on the security. This is mainly be

Resizing an array by a non-constant, continually

I’d like to perform amortized analysis of a dynamic array: When we perform a sequence of n insertions, whenever an array of size k fills up, we reallocate

Optimization of a short-length cyclic convolution

I have two sequences of 8 unsigned bytes and I need to compute their cyclic convolution, which yields 8 unsigned 19 bits integers. As I repeat this million time