Dutch national flag problem: Difference between revisions
Added uBasic/4tH version
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(Added uBasic/4tH version) |
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</pre>
=={{header|uBasic/4tH}}==
This version is based on Edsger Dijkstra's original algorithm. The flag may come out a bit shredded , but it has been assembled the correct way.
<lang>s = 100
For x = 0 To s-1
@(x) = Rnd(3)
Next
' Edsger Dijkstra algorithm starts here
i = 0
j = 0
k = s-1
Do
While j < k+1
If @(j) = 0 Then ' case "red"
Push @(j) : @(j) = @(i) : @(i) = Pop()
i = i + 1 ' fairly efficient exchange
j = j + 1
Else If @(j) = 2 then ' case "blue"
Push @(j) : @(j) = @(k) : @(k) = Pop()
k = k - 1 ' fairly efficient exchange
Else ' you'd expect case "white" here
j = j + 1
Endif Endif
Loop
' end of Dijkstra's algorithm
n = 0
For x = 0 To s-1 ' now show the whole shebang
If @(x) # n Then Print : n = @(x)
Print Chr(Peek ("RWB", @(x)));
Next
Print</lang>
{{Out}}
<pre>RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
0 OK, 0:858</pre>
=={{header|UNIX Shell}}==
{{works with|Bash}}
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