Форум Всеукраїнської інтернет-олімпіади NetOI

const
  maxN = 65535;
var
  N, KK, KSum, i, j, P, Prev, nnew : longint;
  Side : Byte;
  K : array [1..2] of Integer;
  A : array [1..2, 1..maxN] of Word;
  D : array [1..2, 1..maxN] of Byte;
  First : array [1..10000] of Word;
  t : longint;
begin
  Read(N);
  FillChar(D, SizeOf(D), 0);
  for i := 1 to N do
    Read(First[i]);
  for i := 1 to N do
  begin
    Read(t);
    Inc(D[2, t]);
    Inc(D[1, First[i]]);
    if D[1, First[i]] = 2 then
      A[2, First[i]] := t
    else
      A[1, First[i]] := t;
    if D[2, t] = 2 then
      A[1, t] := First[i]
    else
      A[2, t] := First[i];
  end;

  KSum := 0;
  for i := 1 to N do
  begin
    if D[1, First[i]] <> 2 then
      Continue;
    K[1] := 0;
    K[2] := 0;
    KK := 1;
    P := A[1, first[i]];
    D[1, First[i]] := 3;
    K[1] := 1;
    Side := 2;
    Prev := 0;

    while D[1, P] < 3 do
    begin
      if D[Side, P] = 2 then
      begin
        D[Side, P] := 3;
        if Prev=A[1, P] then
          nnew := A[2, P]
        else
          nnew := A[1, P];
        Prev := P;
        P := nnew;
        Side := 3-Side;
        KK := 3-KK;
        Inc(K[KK]);
      end
      else
      begin
        Prev := P;
        P := A[3-Side, P];
        Inc(K[KK]);
      end;
    end;

    if K[1] > K[2] then
      KSum := KSum+K[2]
    else
      KSum := KSum+K[1];
  end;
  Write(KSum);
end.

#include<stdio.h>
#include<math.h>
int main()
{int R,x,y,x1,y1,x2,y2;
scanf("%i %i %i %i %i %i %i",&R,&x,&y,&x1,&y1,&x2,&y2);
double k;
if ((y2-y1)==0)
   {int z;
   z=x; x=y; y=z;
   z=x1; x1=y1; y1=z;
   z=x2; x2=y2; y2=z;
   }
k=((double)x2-x1)/(y2-y1);
double a,b,c;
a=k*k+1.0;
b=2.0*(k*(x1-k*y1-x)-y);
c=k*y1*(k*y1+2.0*(x-x1))+x1*(x1-2.0*x)+x*x+y*y-R*R;
double D;
D=b*b-4.0*a*c;
if (D<0) {printf("-1\n"); return(0);}
if (D==0) {printf("0\n"); return(0);}
double yt1,yt2,xt1,xt2;
yt1=(-b+sqrt(D))/(2.0*a);
yt2=(-b-sqrt(D))/(2.0*a);
xt1=(yt1-y1)*k+x2;
xt2=(yt2-y1)*k+x2;
double rez;
rez=(xt2-xt1)*(xt2-xt1)+(yt2-yt1)*(yt2-yt1);
rez=sqrt(rez);
printf("%-30.16E\n",rez);
return(0);}

(*{$N+,E+}*)
{Type
    Real=Extended;}
Var
    R,x,y,x1,y1,x2,y2,tmp,yp1,yp2,xp1,xp2,k,b:Real;

function Dist(x1,y1,x2,y2:Real):Real;
Begin
    Dist:=Sqrt(Sqr(x2-x1)+Sqr(y2-y1));
End;

Procedure glVertex3f;
Begin
    k:=(y2-y1)/(x2-x1);
    b:=y2-k*x2;
    tmp:=(b*b*k*k-(b*b-R*R)*(1+k*k));
    if tmp < 0 then WriteLn(-1)
    else begin
      tmp:=Sqrt(tmp);
      xp1:=(-b*k+tmp)/(1+sqr(k));
      xp2:=(-b*k-tmp)/(1+sqr(k));
      yp1:=k*xp1+b;
      yp2:=k*xp2+b;
      WriteLn(Dist(xp1,yp1,xp2,yp2));
    end;
End;

Begin
    Read(R,x,y,x1,y1,x2,y2);
    x1:=x1-x;x2:=x2-x;x:=0.0;
    y1:=y1-y;y2:=y2-y;y:=0.0;

    if x1=x2 then begin
      tmp:=Sqr(R)-Sqr(x1);
      if tmp < 0 then WriteLn(-1)
      else if abs(tmp) < 1e-10 then WriteLn(0)
      else WriteLn(sqrt(tmp)*2);
    end
    else if y1=y2 then begin
      tmp:=Sqr(R)-Sqr(y1);
      if tmp < 0 then WriteLn(-1)
      else if abs(tmp) < 1e-10 then WriteLn(0)
      else WriteLn(sqrt(tmp)*2);
    end
    else glVertex3f;
End.

Var
    A:Array[1..40000] of Longint;
    N,i,Sum,nc1,nc2,kc1,kc2,nd2:Longint;
Begin
    Read(N);
    for i:=1 to N do Read(A[i]);
    nd2:=N div 2;
    for i:=1 to nd2 do Inc(Sum,A[i]);
    for i:=nd2+1 to N do begin
       if Sum = N div 4 then begin nc1:=i-nd2-1;nc2:=i-nd2;kc1:=i-1;kc2:=i;break end;
       Inc(Sum,A[i]);Dec(Sum,A[i-nd2]);
    end;
    if nc1=0 then WriteLn('1 ',kc1,' ',kc2)
    else WriteLn('2 ',nc1,' ',nc2,' ',kc1,' ',kc2);
End.

const
  maxN = 65535;
var
  N, KK, KSum, i, j, P, Prev, nnew : longint;
  Side : Byte;
  K : array [1..2] of Integer;
  A : array [1..2, 1..maxN] of Word;
  D : array [1..2, 1..maxN] of Byte;
  First : array [1..10000] of Word;
  t : longint;
begin
  Read(N);
  FillChar(D, SizeOf(D), 0);
  for i := 1 to N do
    Read(First[i]);
  for i := 1 to N do
  begin
    Read(t);
    Inc(D[2, t]);
    Inc(D[1, First[i]]);
    if D[1, First[i]] = 2 then
      A[2, First[i]] := t
    else
      A[1, First[i]] := t;
    if D[2, t] = 2 then
      A[1, t] := First[i]
    else
      A[2, t] := First[i];
  end;

  KSum := 0;
  for i := 1 to N do
  begin
    if D[1, First[i]] <> 2 then
      Continue;
    K[1] := 0;
    K[2] := 0;
    KK := 1;
    P := A[1, first[i]];
    D[1, First[i]] := 3;
    K[1] := 1;
    Side := 2;
    Prev := 0;

    while D[1, P] < 3 do
    begin
      if D[Side, P] = 2 then
      begin
        D[Side, P] := 3;
        if Prev=A[1, P] then
          nnew := A[2, P]
        else
          nnew := A[1, P];
        Prev := P;
        P := nnew;
        Side := 3-Side;
        KK := 3-KK;
        Inc(K[KK]);
      end
      else
      begin
        Prev := P;
        P := A[3-Side, P];
        Inc(K[KK]);
      end;
    end;

    if K[1] > K[2] then
      KSum := KSum+K[2]
    else
      KSum := KSum+K[1];
  end;
  Write(KSum);
end.