why wa2?I have tried many tests,and output the right answer,but WA2
Posted by
uuu 1 Sep 2010 20:20
var
i,j,k,n,m,tot:longint;
ans,x1,y1,x2,y2,d1,d2,d3,x,y,angle1,angle2,t,p1,p2:double;
function min(xx,yy:double):double;
begin
if xx>yy then exit(yy);
exit(xx);
end;
begin
{assign(input,'1215.in');reset(input);}
read(x,y,n);
read(x1,y1);
p1:=x1;
p2:=y1;
d1:=sqrt(sqr(x-x1)+sqr(y-y1));
ans:=999999999;
tot:=0;
for i:=2 to n do
begin
read(x2,y2);
if (x1<x)and(x2>=x)and((y1<y)or(y2<y))
then
inc(tot);
d2:=sqrt(sqr(x-x2)+sqr(y-y2));
d3:=sqrt(sqr(x1-x2)+sqr(y1-y2));
angle1:=(d2*d2+d3*d3-d1*d1)/(2*d2*d3);
angle2:=(d1*d1+d3*d3-d2*d2)/(2*d1*d3);
if (angle1>=0)and(angle2>=0)
then
begin
if x1=x2
then
t:=abs(x1-x)
else
t:=((y1-y2)/(x1-x2)*x-y+y1+(y2-y1)/(x1-x2)*x1)/(sqrt(sqr((y1-y2)/(x1-x2))+1));
t:=abs(t);
ans:=min(ans,t);
end
else
begin
t:=min(d1,d2);
ans:=min(ans,t);
end;
d1:=d2;
x1:=x2;
y1:=y2;
end;
x2:=p1;
y2:=p2;
if (x1<x)and(x2>=x)and((y1<y)or(y2<y))
then
inc(tot);
d2:=sqrt(sqr(x-x2)+sqr(y-y2));
d3:=sqrt(sqr(x1-x2)+sqr(y1-y2));
angle1:=(d2*d2+d3*d3-d1*d1)/(2*d2*d3);
angle2:=(d1*d1+d3*d3-d2*d2)/(2*d1*d3);
if (angle1>=0)and(angle2>=0)
then
begin
if x1=x2
then
t:=abs(x1-x)
else
t:=((y1-y2)/(x1-x2)*x-y+y1+(y2-y1)/(x1-x2)*x1)/(sqrt(sqr((y1-y2)/(x1-x2))+1));
t:=abs(t);
ans:=min(ans,t);
end
else
begin
t:=min(d1,d2);
ans:=min(ans,t);
end;
if odd(tot)
then
ans:=0;
writeln(ans*2:0:3);
end.