De thi Toan Tin hoc trong nha truong Bai 7

BEGIN Clrscr; Nhap; Chuanbi; Tinhslmien; GhiKQ; END..[r]

Bài 7/1999 - Miền mặt phẳng chia đường thẳng (Dành cho học sinh THPT)

Program Bai7;

(* Tinh so giao diem cua n duong thang ko trung *) Uses Crt;

Const

fn = 'P7.INP'; fg = 'P7.OUT'; max = 100; exp = 0.0001; Var

a ,b ,c : array[1 max] of real; n : integer;

smien : integer; Procedure Nhap; Var

f : text; i : integer; Begin

Assign( f ,fn ); Reset( f ); Readln( f ,n );

For i := to n

Readln( f ,a[i] ,b[i] ,c[i] ); { ax + by = c } Close( f );

End;

(* -*) Procedure Chuanbi;

Begin smien := 1; End;

(* -*) Function Giaodiem( i ,j : integer;Var x ,y : real ) : boolean; Var

d ,dx ,dy :real; Begin

d := a[i] * b[j] - a[j] * b[i]; dx:= c[i] * b[j] - c[j] * b[i]; dy := a[i] * c[j] - a[j] * c[i]; If d <> then

begin x := dx / d; y := dy / d; end;

Giaodiem := d <> 0; End;

Function Giatri( i : integer;x ,y : real ) : real; Begin

Giatri := a[i] * x + b[i] * y - c[i]; End;

(* -*) Function bang( a ,b : real ) : boolean;

Begin

bang := abs( a - b ) <= exp; End;

(* -*) Function Thoaman( i : integer;x ,y : real ) : boolean;

Var

ii : integer; Begin

Thoaman := false; For ii := to i -

If bang( Giatri( ii ,x ,y ) ,0 ) then exit;

Thoaman := true; End;

(* -*) Function Cattruoc( i : integer ) : integer;

Var

ii , gt : integer; x, y : real; Begin gt:= 0;

For ii := to i -

If Giaodiem( i ,ii ,x ,y ) then If Thoaman( ii ,x ,y ) then Inc( gt ); cattruoc := gt;

End;

(* -*) Procedure Tinhslmien;

Var i : integer; Begin

For i := to n

Inc( smien ,cattruoc( i ) + ); End;

(* -*) Procedure GhiKQ;

Begin

Writeln(So mien mat phang duoc chia la: ' ,smien ); End;