All factors of a given number

In Ruby, the prime library gives you the factorization: require ‘prime’ 4800.prime_division #=> [[2, 6], [3, 1], [5, 2]] To get that list of yours, you take the cartesian product of the possible powers: require ‘prime’ def factors_of(number) primes, powers = number.prime_division.transpose exponents = powers.map{|i| (0..i).to_a} divisors = exponents.shift.product(*exponents).map do |powers| primes.zip(powers).map{|prime, power| prime ** … Read more

Why is Insertion sort better than Quick sort for small list of elements?

Big-O Notation describes the limiting behavior when n is large, also known as asymptotic behavior. This is an approximation. (See http://en.wikipedia.org/wiki/Big_O_notation) Insertion sort is faster for small n because Quick Sort has extra overhead from the recursive function calls. Insertion sort is also more stable than Quick sort and requires less memory. This question describes … Read more

Printing BFS (Binary Tree) in Level Order with Specific Formatting

Just build one level at a time, e.g.: class Node(object): def __init__(self, value, left=None, right=None): self.value = value self.left = left self.right = right def traverse(rootnode): thislevel = [rootnode] while thislevel: nextlevel = list() for n in thislevel: print n.value, if n.left: nextlevel.append(n.left) if n.right: nextlevel.append(n.right) print thislevel = nextlevel t = Node(1, Node(2, Node(4, … Read more

Non-Recursive Merge Sort

Non-recursive merge sort works by considering window sizes of 1,2,4,8,16..2^n over the input array. For each window (‘k’ in code below), all adjacent pairs of windows are merged into a temporary space, then put back into the array. Here is my single function, C-based, non-recursive merge sort. Input and output are in ‘a’. Temporary storage … Read more

How to implement an A* algorithm? [closed]

This article explains the basic implementation in length: The goal of this blog post is to show the fundamentals of A* through a really simple C# implementation. It also points to better implementations, more suitable for production use: As for ways to find better routes, there are plenty of C# examples around that are far … Read more