记录编号	78734	评测结果	AAAAAAAAAA
题目名称	[NOIP 2010冲刺十二]圆圈舞蹈	最终得分	100
用户昵称	gungnir	是否通过	通过
代码语言	Pascal	运行时间	0.139 s
提交时间	2013-11-04 14:47:17	内存使用	0.49 MiB

var   n,i,x,j,t1,t2,re:longint;
      f:array[0..100005]of longint;

begin
assign(input,'circlea.in');reset(input);
assign(output,'circlea.out');rewrite(output);
readln(n);
for i:=2 to n+1 do
begin
readln(x);
f[i]:=f[i-1]+x;
end;

j:=1; re:=0;
for i:=2 to n do
begin
t1:=f[i]-f[j];
t2:=f[n+1]-t1;
  if t1>t2 then
  begin
    while t2<=t1 do
    begin
    if t2>re then re:=t2;
    inc(j);
    if j>=n then begin j:=n; break; end;
    t1:=f[i]-f[j];
    t2:=f[n+1]-t1;
    if(t2>t1)and(t1>re) then re:=t1;
    end;
  end
  else begin
    while(t2>=t1)do
    begin
    if t1>re then re:=t1;
    dec(j);
    if j<=0 then begin j:=1; break; end;
    t1:=f[i]-f[j];
    t2:=f[n+1]-t1;
    if(t2<t1)and(re<t2)then re:=t2;
    end;
  end;
end;
writeln(re);
close(input);close(output);
end.