A simple bubble sort which arranges the provided array of numbers from smallest to largest.
static void BubbleSort(ref int[] arr)
{
bool change = true;
int temp;
while (change)
{
change = false;
for (int i = 0; i < arr.GetLength(0) - 1; i++)
{
if (arr[i + 1] < arr[i])
{
change = true;
temp = arr[i];
arr[i] = arr[i + 1];
arr[i + 1] = temp;
break;
}
}
}
}
Anders Bjorkman (Heiwa) is completely nuts , check out the crazy things he believes.
https://sites.google.com/site/wtc7lies/home/anders-bjorkman-s-world
The RPi requires an SD Card in order to install an operating system (which I haven’t got), a mouse and keyboard (which I have) and something to connect its HDMI display to a monitor. As a Mac user this represents a problem, as I don’t have any displays with HDMI connectors on. However, I do have a 23″ Apple Cinema Display and a converter which converts the proprietary Apple connector to DVI output, so all I need is a DVI to VGA connector, a VGA to HDMI connector and a female to female VGA converter.
I have acquired a Raspberry Pi Model B with the intention of doing some development work for a friend, and this blog shall document my findings, works, inevitable frustrations and, hopefully, my successes.
Have you ever been frustated by the ToolTip component’s lack of functionality, i.e. you’t can add a close button like the NotifyIcon control, lack of handleable events? Be frustated no more, as a solution is at hand.
The Balloon Window for .Net will is a handy addon that offers all the functionality of the NotifyIcon control AND the ToolTip in a handy package.
Recently I decided to learn C and have been diligently working my way through tutorials and websites, and since I’m more familiar with high level languages (C# for example) getting used to the more low level C is proving to be a challenge.
After getting to grips with the dreaded pointers I immediately ran into the problem of how to return an array from a function – the familiar methods used by anyone familiar with C# or VB.Net don’t work, and attempts at implementing return unusual results. Basically, populating an array in a function and passing a reference to it is doomed to fail it’s a regular local variable, with automatic duration, which means that it springs into existence when the function is called and disappears when the function returns. Passing a reference out of a function to a variable that has expired points to an junk.
After some googling, I found a helpful document that describes how to deal with the problem on http://c-faq.com, which describes in the three methods of returning arrays from functions which, briefly, are:
All three methods have their own positives and negatives, but for the purposes on what I’m doing I’m going for the second one.
'
' Process a column of values, colouring alternate ranges of the same value.
'
' Work down a column of cells, stopping when a blank is hit.
'
' If a cell is a different value to the one preceding it, invert the
' value of the toggle variable.
'
' If the toggle variable is true colour the cell.
'
Public Sub main()
Dim w As Worksheet
Set w = Worksheets("Sheet1")
Dim rowCtr As Integer
rowCtr = 2
Dim toggle As Boolean
toggle = False
While w.Cells(rowCtr, 1).Value <> ""
If rowCtr > 2 Then
If w.Cells(rowCtr, 2).Value <> w.Cells(rowCtr - 1, 2).Value Then
toggle = Not toggle
End If
End If
If toggle Then
With w.Cells(rowCtr, 2).Interior
.ColorIndex = 6
.Pattern = xlSolid
End With
End If
rowCtr = rowCtr + 1
Wend
End Sub
I worked out an implementation of the Sieve of Atkin for use in solving Project Euler problems. It’s probably not as efficient as it could be, but it does the trick for me.
set nocount on drop table #atkin create table #atkin ( num float , isPrime bit ) create clustered index primenums on #atkin(num) declare @limit as bigint declare @sqrt as float declare @x as int declare @y as int declare @n as int set @limit = 1000000 set @sqrt = sqrt(@limit) set @x = 1 print 'begin outer loop' /* put in candidate primes: integers which have an odd number of representations by certain quadratic forms */ while (@x <= @sqrt) begin set @y = 1 while (@y <=@sqrt) begin set @n = (4 * (@x * @x)) + (@y * @y) if ((select num from #atkin where num =@n) is null) insert into #atkin (num, isPrime) values (@n,0) if (@n <= @limit AND (@n % 12 = 1 or @n % 12 =5)) update #atkin set isPrime = isPrime ^ 1 where num = @n set @n = (3 * (@x * @x)) + (@y * @y) if ((select num from #atkin where num =@n) is null) insert into #atkin (num, isPrime) values (@n,0) if (@n <= @limit AND @n % 12 = 7) update #atkin set isPrime = isPrime ^ 1 where num = @n set @n = (3 * (@x * @x)) - (@y * @y) if ((select num from #atkin where num =@n) is null) insert into #atkin (num, isPrime) values (@n,0) if (@x >= @y AND @n <= @limit AND @n % 12 = 11) update #atkin set isPrime = isPrime ^ 1 where num = @n set @y = @y + 1 end set @x = @x + 1 end declare @nsqr as bigint declare @k as bigint /* eliminate composites by sieving */ set @n = 5 while ( @n <= @sqrt) begin print @n if ((select isprime from #atkin where num = @n)=1) begin set @nsqr = @n * @n set @k = @nsqr while (@k <= @limit) begin update #atkin set isPrime = 0 where num = @k set @k = @k + @nsqr print '@k increment ' + str(@k) end end set @n = @n + 1 print '@n increment ' + str(@n) end insert into #atkin (num, isPrime) values (2,1) insert into #atkin (num, isPrime) values (3,1) delete from #atkin where isprime <> 1
This is a solution for Project Euler Problem 37. It makes uses of a temporary table called #atkin which is populated with prime numbers using the TSQL routine that uses the Sieve of Atkin, which is also located on this site.
Easy! There are, however, a couple of deliberate errors, that can be easily located with some patience. I don’t want to make things to easy for you little scamps, do I?
/*
process the prime number list
*/
/*
the number we are examining can't be single digits or contain zeros
*/
drop table #candidates
select num
into #candidates
from #atkin
where charindex('0', cast(num as varchar)) = 0
declare @ctr as integer
declare @del as integer
set @ctr = 1
set @del = 0
/*
delete from the candidate list any number that doesn't have a
shorter counterpart in the list of prime numbers, increasing
the string size by 1 with every loop, and bailing out of when
we stop deleting things
*/
while (@del > 0)
begin
delete from #candidates
from #candidates c1
left outer join #atkin a1
on left(c1.num,@ctr) = a1.num
left outer join #atkin a2
on right(c1.num,@ctr) = a2.num
where a1.num is null
or a2.num is not null
set @del = @@rowCount
set @ctr = @ctr + 1
end
/*
output the answer
*/
select sum(num)
from #candidates