Tin học - Bài 56: Chia lưới

Bài 56/2001 - Chia lưới
(Dành cho học sinh PTTH)
Program Chia_luoi ;
Uses Crt ;
Const Fi = 'LUOI.INP';
 Fo = 'LUOI.OUT';
Var A : Array[1..20,1..20]Of Integer ;
 B : Array[1..20,1..20]Of 0..1 ;
 Px,Py: Array[1..4] Of ShortInt ;
 M,N,S,S1,S2 : LongInt ;
 F : Text ;
Procedure Read_Input ;
 Var i,j :Integer;
Begin
 Clrscr ; S:= 0 ;
 Assign(F,Fi) ;Reset(F) ;
 Readln(F,M,N);
 For i:=1 to M do
 Begin
 For j:=1 to N do
 Begin
 Read(F,A[i,j]);
 S:=S+A[i,j];
 End;
 Readln(F);
 End;
 Close(F);
End;
 Procedure Innit ;
 Begin
 S1 := S div 2;
 Px[1]:= 0 ;Px[2]:= 0 ;Px[3]:=1 ;Px[4]:=-1 ;
 Py[1]:= 1 ;Py[2]:=-1 ;Py[3]:=0 ;Py[4]:= 0 ;
 End ;
Procedure Write_Output ;
 Var i,j :Integer;
Begin
 Assign(F,Fo); ReWrite(F);
 For i:=1 to M do
 Begin
 For j:=1 to N do
 Write(F,B[i,j],' ');
 Writeln(F);
 End;
 Close(F);Halt;
End;
Function Ktra(x,y : Integer) : Boolean ;
Begin
 Ktra:= False ;
 If (x in [1..M]) And (y in [1..N]) And
 (B[x,y] = 0 ) Then Ktra := True ;
End;
Procedure Try(x,y:Integer ;Sum :LongInt);
 Var i :Integer ;
Begin
 For i:=1 to 4 do
 If Ktra(x+Px[i],y+Py[i]) Then
 Begin
 x := x + Px[i] ;
 y := y + Py[i] ;
 Sum := Sum + A[x,y];
 B[x,y] := 1;
 If Sum = S2 Then Write_Output ;
 Try(x,y,Sum) ;
 Sum := Sum - A[x,y];
 B[x,y] := 0;
 x := x - Px[i] ;
 y := y - Py[i] ;
 End ;
End;
Procedure Run ;
 Var i,j : Integer ;
Begin
 Read_Input ;Innit ;
 For i:=1 to M do
 For j:=1 to N do
 If A[i,j]>= S1 Then
 Begin
 Fillchar(B,SizeOf(B),0);
 B[i,j]:=1;
 Write_Output;
 End ;
 For S2 := S1 downto 1 do
 Begin
 Fillchar(B,SizeOf(B),0);
 B[1,1]:=1;
 Try(1,1,A[1,1]);
 End;
End;
BEGIN 
 Run; 
END.
(Lời giải của bạn Lê Sơn Tùng - Vĩnh Phúc )