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## Discussion of Problem 1159. Fence

Why I get WA? Pelase, help me!!!!!!! (+)
Posted by Nazarov Denis (nsc2001@rambler.ru) 1 Feb 2002 19:21
My program:

Program t1159;{\$N+}

Const MaxN   = 100;
Change = 180/Pi;
OkW    = 360.0;
Eps    = 1E-15;
Eps2   = 1E-3;

Var   Block        : array[1..MaxN]of integer;
N,i,sum,max  : integer;
mx,t         : integer;
left,rigth   : extended;
middle       : extended;
curW         : extended;
ok           : boolean;

Function GetLW(R : extended;L : integer) : extended;
Var cosw,w,tgw  : extended;
begin
cosw:=(2*R*R-L*L)/(2*R*R);
if cosw=0 then w:=90 else begin
tgw:=sqrt(1-cosw*cosw)/cosw;
w:=ArcTan(tgw)*Change;
if w<0 then w:=180+w;
end;
GetLW:=w;
end;

Function GetW(R : extended) : extended;
Var w     : extended;
j     : integer;
begin
w:=0;
for j:=1 to N do w:=w+GetLW(R,Block[j]);
GetW:=w;
end;

Function GetS(R : extended) : extended;
Var Ans,p,S  : extended;
i        : integer;
begin
Ans:=0;
for i:=1 to N do begin
p:=(2*R+Block[i])/2;
S:=sqrt(abs(p*(p-R)*(p-R)*(p-Block[i])));
Ans:=Ans+S;
end;
GetS:=Ans;
end;

Procedure WriteAns(R : extended);
begin
Writeln(GetS(R):0:2);
Halt(0);
end;

Procedure WriteAns2(R : extended);
Var S,p  : extended;
begin
p:=(2*R+Block[N+1])/2;
S:=sqrt(p*(p-R)*(p-R)*(p-Block[N+1]));
Writeln(GetS(R)-S:0:2);
{Halt(0);}
end;

begin
sum:=0;
max:=0;
for i:=1 to N do begin
sum:=sum+Block[i];
if Block[i]>max then begin
max:=Block[i];
mx:=i;
end;
end;
if mx<>N then begin
t:=Block[mx];
Block[mx]:=Block[N];
Block[N]:=t;
end;
if max>=sum-max then begin
writeln('0.00');
halt(0);
end;
if max mod 2=0 then max:=max div 2 else max:=1+(max div 2);
left:=max;
rigth:=sum;
While True do begin
middle:=(left+rigth)/2;
curW:=GetW(middle);
if curW<OkW then rigth:=middle else left:=middle;
if rigth-left<Eps then break;
end;
if abs(curW-OkW)<Eps2 then WriteAns(middle);
N:=N-1;
left:=max;
rigth:=1E10;
While True do begin
middle:=(left+rigth)/2;
curW:=GetW(middle);
if curW>GetLW(middle,Block[N+1]) then rigth:=middle else
left:=middle;
if rigth-left<Eps then break;
end;
writeans2(middle);
end.