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The answers will be published a week after the quiz has started!
Computer Algorithms: Shell Sort
Overview
Insertion sort is a great algorithm, because it’s very intuitive and it is easy to implement, but the problem is that it makes many exchanges for each “light” element in order to put it on the right place. Thus “light” elements at the end of the list may slow down the performance of insertion sort a lot. That is why in 1959 Donald Shell proposed an algorithm that tries to overcome this problem by comparing items of the list that lie far apart.
In the other hand it is obvious that by comparing items that lie apart the list can’t be sorted in one pass as insertion sort. That is why on each pass we should use a fixed gap between the items, then decrease the value on every consecutive iteration. Continue reading Computer Algorithms: Shell Sort
Computer Algorithms: Bubble Sort
Overview
It’s weird that bubble sort is the most famous sorting algorithm in practice since it is one of the worst approaches for data sorting. Why is bubble sort so famous? Perhaps because of its exotic name or because it is so easy to implement. First let’s take a look on its nature.
Bubble sort consists of comparing each pair of adjacent items. Then one of those two items is considered smaller (lighter) and if the lighter element is on the right side of its neighbour, they swap places. Thus the lightest element bubbles to the surface and at the end of each iteration it appears on the top. I’ll try to explain this simple principle with some pictures.
1. Each two adjacent elements are compared
Here “2” appears to be less than “4”, so it is considered lighter and it continues to bubble to the surface (the front of the array).
Continue reading Computer Algorithms: Bubble Sort
jQuery UI Slider IE bugfix
Do your jQuery slider brakes under IE too?
When you want to null the sliders on an page, using jQuery UI Slider, somehow the following code works in any browser except IE.
// wrong $('.my-slider').slider('value', 0); |
I say somehow, because according to the documentation this code is simply wrong. It can be used to get the value of the slider as it is a getter. You can null the value with the following snippet.
// correct $('.my-slider').slider('option', 'value', 0); |
IE Fix
Another way to null the value is with an anonymous object.
// correct $('.my-slider').slider({ value: 0 }); |
This works on every browser including IE.
Computer Algorithms: Insertion Sort
Overview
Sorted data can dramatically change the speed of our program, therefore sorting algorithms are something quite special in computer science. For instance searching in a sorted list is faster than searching in an unordered list.
There are two main approaches in sorting – by comparing the elements and without comparing them. A typical algorithm from the first group is insertion sort. This algorithm is very simple and very intuitive to implement, but unfortunately it is not so effective compared to other sorting algorithms as quicksort and merge sort. Indeed insertion sort is useful for small sets of data with no more than about 20 items.
Insertion sort it is very intuitive method of sorting items and we often use it when we play card games. In this case the player often gets an unordered set of playing cards and intuitively starts to sort it. First by taking a card, making some comparisons and then putting the card on the right position.
So let’s say we have an array of data. In the first step the array is unordered, but we can say that it consists of two sub-sets: sorted and unordered, where on the first step the only item in the sorted sub-set is its first item. If the length of the array is n the algorithm is considered completed in n-1 steps. On each step our sorted subset is growing with one item. The thing is that we take the first item from the unordered sub-set and with some comparisons we put it into its place in the sorted sub-set, like on the diagram bellow.
Continue reading Computer Algorithms: Insertion Sort