program _matrix_;

uses crt; { needed for "clrscr" only }

const max_size=7; { <-- side size for matrix (i.e 7x7) }

type matrix_element=integer; { <-- type of an element }
     { matrix in 2D }
     matrix=array[1..max_size,1..max_size] of matrix_element;
     { matrix in 1D, surveyed }
     msurveyed=array[1..max_size*max_size] of matrix_element;


var i,j,k:byte;
    mx,my,dir,step:byte;
    m2d:matrix;
    m1d:msurveyed;
    trigs:array[1..max_size*max_size] of boolean; { direction triggers }


begin
 writeln;
 for i:=1 to max_size do  { get user to input matrix elements }
  for j:=1 to max_size do begin
   write('Enter element [',j,',',i,']  > ');readln(m2d[j,i]);
  end;

 clrscr;
 writeln('Matrix in 2D :');
 for i:=1 to max_size do         { display 2D matrix }
  for j:=1 to max_size do begin
   gotoxy(j*3,i*2);
   write(m2d[j,i]);
  end;
 writeln;
 writeln(#13#10,'Matrix in 1D :');

 mx:=max_size div 2+1;   { calculate midpoint }
 my:=mx;
 dir:=3;                 { initial direction }
 if not(odd(max_size)) then begin dec(mx);dir:=1;end;{ adjust for even numbers }

 fillchar(trigs,0,sizeof(trigs)); { init triggers with false ("0") }

 step:=1;
 k:=1;
 for i:=1 to max_size do begin    { calculate direction triggers }
   inc(k,step);
   if k<=max_size*max_size then trigs[k]:=true;
   inc(k,step);
   if k<=max_size*max_size then trigs[k]:=true;
   inc(step);
 end;

 k:=max_size*max_size;

 m1d[k]:=m2d[mx,my];  { get first element based on the calculations above }

 for i:=2 to k do begin { do the spiral survey }
   case dir of
    1:{right}inc(mx);
    2:{up   }dec(my);
    3:{left }dec(mx);
    4:{down }inc(my);
   end;
   m1d[k-pred(i)]:=m2d[mx,my];
   if trigs[i] then  {direction trigger}
    if dir=4 then dir:=1 else inc(dir);
 end;

 for i:=1 to k do    { display 1D matrix }
  write(m1d[i],', ');
 writeln;
 readln;
end.

Type
   Matrix = array [1 .. 7, 1 .. 7] of Integer ;
   Survey = array [1 .. 49] of Integer ;

   Procedure DoSurvey (Var S : Survey ; M : Matrix) ;
   begin
      S[1]  := M[1,1] ;
      S[2]  := M[2,1] ;
      S[3]  := M[3,1] ;
      S[4]  := M[4,1] ;
      S[5]  := M[5,1] ;
      S[6]  := M[6,1] ;
      S[7]  := M[7,1] ;
      S[8]  := M[7,2] ;
      S[9]  := M[7,3] ;
      S[10] := M[7,4] ;
      S[11] := M[7,5] ;
      S[12] := M[7,6] ;
      S[13] := M[7,7] ;
      S[14] := M[6,7] ;
      S[15] := M[5,7] ;
      S[16] := M[4,7] ;
      S[17] := M[3,7] ;
      S[18] := M[2,7] ;
      S[19] := M[1,7] ;
      S[20] := M[1,6] ;
      S[21] := M[1,5] ;
      S[22] := M[1,4] ;
      S[23] := M[1,3] ;
      S[24] := M[1,2] ;
      S[25] := M[2,2] ;
      S[26] := M[3,2] ;
      S[27] := M[4,2] ;
      S[28] := M[5,2] ;
      S[29] := M[6,2] ;
      S[30] := M[6,3] ;
      S[31] := M[6,4] ;
      S[32] := M[6,5] ;
      S[33] := M[6,6] ;
      S[34] := M[5,6] ;
      S[35] := M[4,6] ;
      S[36] := M[3,6] ;
      S[37] := M[2,6] ;
      S[38] := M[2,5] ;
      S[39] := M[2,4] ;
      S[40] := M[2,3] ;
      S[41] := M[3,3] ;
      S[42] := M[4,3] ;
      S[43] := M[5,3] ;
      S[44] := M[5,4] ;
      S[45] := M[5,5] ;
      S[46] := M[4,5] ;
      S[47] := M[3,5] ;
      S[48] := M[3,4] ;
      S[49] := M[4,4]
   end ;