Find first missing positive: Difference between revisions

=={{header|Delphi}}==

{{works with|Delphi|6.0}}

{{libheader|SysUtils,StdCtrls}}

Uses the Delphi "TList" object to search the list for missing integers.

<syntaxhighlight lang="Delphi">

var List1: array [0..2] of integer =(1,2,0);

var List2: array [0..3] of integer =(3,4,-1,1);

var List3: array [0..4] of integer =(7,8,9,11,12);

function FindMissingInt(IA: array of integer): integer;

var I,Inx: integer;

var List: TList;

begin

List:=TList.Create;

try

Result:=-1;

for I:=0 to High(IA) do List.Add(Pointer(IA[I]));

for Result:=1 to High(integer) do

begin

Inx:=List.IndexOf(Pointer(Result));

if Inx<0 then exit;

end;

finally List.Free; end;

end;

function GetIntStr(IA: array of integer): string;

var I: integer;

begin

Result:='[';

for I:=0 to High(IA) do

begin

if I>0 then Result:=Result+',';

Result:=Result+Format('%3.0d',[IA[I]]);

end;

Result:=Result+']';

end;

procedure ShowMissingInts(Memo: TMemo);

var S: string;

var M: integer;

begin

S:=GetIntStr(List1);

M:=FindMissingInt(List1);

Memo.Lines.Add(S+' = '+IntToStr(M));

S:=GetIntStr(List2);

M:=FindMissingInt(List2);

Memo.Lines.Add(S+' = '+IntToStr(M));

S:=GetIntStr(List3);

M:=FindMissingInt(List3);

Memo.Lines.Add(S+' = '+IntToStr(M));

end;

</syntaxhighlight>

{{out}}

<pre>

[ 1, 2, 0] = 3

[ 3, 4, -1, 1] = 2

[ 7, 8, 9, 11, 12] = 1

</pre>