84 lines
1.8 KiB
Plaintext
84 lines
1.8 KiB
Plaintext
var
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a: array[0 .. 3] of shortint;
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function largest_digit(n: smallint): shortint;
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var
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m: shortint;
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begin
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m := n div 1000;
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if m < n mod 1000 div 100 then
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m := n mod 1000 div 100;
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if m < n mod 100 div 10 then
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m := n mod 100 div 10;
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if m < n mod 10 then
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exit(n mod 10)
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else
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exit(m)
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end;
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procedure sort_digits(n: smallint);
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var
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i, j: shortint;
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begin
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a[0] := n div 1000;
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a[1] := n mod 1000 div 100;
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a[2] := n mod 100 div 10;
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a[3] := n mod 10;
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for i := 0 to 2 do
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for j := i + 1 to 3 do
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if a[i] < a[j] then
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begin
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inc(a[i], a[j]);
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a[j] := a[i] - a[j];
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dec(a[i], a[j])
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end
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end;
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function desc_digits(n: smallint): smallint;
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begin
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sort_digits(n);
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exit(a[0] * 1000 + a[1] * 100 + a[2] * 10 + a[3])
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end;
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function kaprekar(n: smallint): qword;
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var
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i: shortint = 0;
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begin
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while n <> 6174 do
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begin
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inc(i);
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sort_digits(n);
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n := (a[0] - a[3]) * 999 + (a[1] - a[2]) * 90
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end;
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exit(i)
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end;
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begin
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writeln('largest_digit(1234) -> ', largest_digit(1234));
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writeln('largest_digit(3253) -> ', largest_digit(3253));
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writeln('largest_digit(9800) -> ', largest_digit(9800));
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writeln('largest_digit(3333) -> ', largest_digit(3333));
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writeln('largest_digit(120) -> ', largest_digit(120));
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writeln;
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writeln('desc_digits(1234) -> ', desc_digits(1234));
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writeln('desc_digits(3253) -> ', desc_digits(3253));
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writeln('desc_digits(9800) -> ', desc_digits(9800));
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writeln('desc_digits(3333) -> ', desc_digits(3333));
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writeln('desc_digits(120) -> ', desc_digits(120));
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writeln;
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writeln('kaprekar(6589) -> ', kaprekar(6589));
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writeln('kaprekar(5455) -> ', kaprekar(5455));
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writeln('kaprekar(6174) -> ', kaprekar(6174))
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end.
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