Sunday, December 5, 2010

Gnome Sort

Gnome sort, originally proposed by Hamid Sarbazi-Azad in 2000 and called Stupid sort, and then later on described by Dick Grune and named "Gnome sort", is a sorting algorithm which is similar to insertion sort, except that moving an element to its proper place is accomplished by a series of swaps, as in bubble sort.

It is conceptually simple, requiring no nested loops. The running time is O(n2), but tends towards O(n) if the list is initially almost sorted. In practice the algorithm can run as fast as Insertion sort. The average runtime is O(n2)

The algorithm always finds the first place where two adjacent elements are in the wrong order, and swaps them. It takes advantage of the fact that performing a swap can introduce a new out-of-order adjacent pair only right before or after the two swapped elements. It does not assume that elements forward of the current position are sorted, so it only needs to check the position directly before the swapped elements.

public IList GnomeSort(IList arrayToSort)
    int pos = 1;
    while (pos < arrayToSort.Count)
        if (((IComparable)arrayToSort[pos]).CompareTo(arrayToSort[pos - 1]) >= 0)
            object temp = arrayToSort[pos];
            arrayToSort[pos] = arrayToSort[pos - 1];

            arrayToSort[pos - 1] = temp;
            RedrawItem(pos - 1);
            if (savePicture)
            if (pos > 1)
    return arrayToSort;

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