# DS&A

Data Structures and Algorithms

## Choose the Right Data Types

Apr 302018

One of the most important and overlooked parts of designing algorithms is choosing the right data types. We often assume that the types of data an algorithm will use are determined by the inputs and the output — but it might help to use a temporary collection of some data, if that collection has useful operations. Those operations are determined by the collection’s type.

In this post we’ll look at a couple of examples where using the right data types makes the problem simpler.

## Algorithm Strategies

Apr 302018

Perhaps the most difficult part of our process for writing algorithms is splitting a problem into subproblems. This is more an art than a science — there’s no systematic way to identify subproblems, and each problem might be split into subproblems in many different ways.﻿(1)

## Simple Shapes

Apr 232018

The most primitive geometric objects are points and vectors. But real geometric problems involve shapes like rectangles, triangles, circles, and polygons — or more complex collections of shapes, such as 3D models made of many polygons. In this post we’ll consider how computers can represent some simple kinds of shapes, and solve problems using these representations.

## Recursive Sorting

Apr 162018

In the previous post we saw two iterative sorting algorithms: selection sort and insertion sort both work using a loop to put the right values in the right places, one at a time. They are two of the simplest sorting algorithms. But they’re not very efficient — for long lists, they’re too slow.﻿(1)

In this post we’ll see one of the simplest efficient sorting algorithms, called merge sort. Rather than sorting items one-by-one, it works by recursively sorting shorter lists.

## Iterative Sorting

Apr 162018

Before writing an algorithm, it’s always worth thinking about how you would solve the same problem “by hand”. After all, you can’t write instructions for how to do something if you don’t know how to do it yourself.

The problem we’re currently interested in is sorting — given a list, put its values in order. There are hundreds of algorithms which solve this problem, but ultimately every sorting algorithm does one of two things:

## Comparisons and Swaps

Apr 162018

We have seen two search algorithms on lists — linear search and binary search. Both algorithms find the index of a given target value in a list. But they make different assumptions about the data in the list: linear search works on any list, whereas binary search only works if the list is in order.

Atom

hosted on werp.site