Substraightstring.pas

//Do phuc tap O(n)
var
    fi,fo:text;
    k,i,j,n,dem,max:longint;
    a: array [1..1000000] of longint;
    check:boolean;
begin
    assign(fi,'INPUT.INP');
    assign(fo,'OUTPUT.OUT');
    reset(fi);
    rewrite(fo);
    readln(fi,n);
    for i:=1 to n do
    read(fi,a[i]);
    i:=0;
    max:=0;
    while i<=(n-2) do
        begin
            inc(i);
            dem:=1;
            if (a[i] = a[i+1]) and (i < n) then //Tim thay truong hop thoa man
                while ( a[i] = a[i+1] ) and ( i<n ) do
                    begin
                        inc(i);
                        dem:=dem+1;
                    end;
            if dem>max then max:= dem;
        end;
    if max < 2 then //Max = 1 , Max=0 thi STOP
        begin
            write(fo,'KHONG TON TAI');
            close(fo);
            close(fi);
            exit;
        end;
        write(fo,max);
        writeln(fo);
    for i:=1 to n-max+1 do
    begin
        check:=true;
        for j:=i to i+max-2 do
            if (a[j]<>a[j+1]) and (j<n) then check:=false;
        if check then
            for k:=i to i+max-1 do write(fo,a[k],' ');
        if check then
            writeln(fo);
    end;
    close(fi);
    close(fo);
end.