寄信人: sino (蚱蜢舟)
标 题: 1118
发信站: 哈工大紫丁香 (2002年03月23日15:27:03 星期六)
来 源: mtlab4.hit.edu.cn
171243 07:29:24 23 Mar 2002
Bozhang,HIT,P.R.China 1118 Pascal Accepted 1.512 sec 364K
var
p:array[1..78498] of integer;
i,j,k,e,best:integer;
a,b:extended;
f:boolean;
begin
p[1]:=2; k:=1;
for i:=3 to 1000000 do begin
f:=true; if k<168 then e:=k else e:=168;
for j:=1 to e do if i mod p[j]=0 then begin
f:=false; break;
end;
if f then begin
inc(k);
p[k]:=i;
end;
end;
readln(i,j);
if i=1 then begin
writeln(1);
halt
end;
for k:=78498 downto 1 do begin
if p[k]<i then break;
if p[k]<=j then begin
writeln(p[k]);
halt;
end;
end;
for k:=168 downto 1 do begin
e:=p[k]*p[k];
if (e>=i) and (e<=j) then begin
writeln(e);
halt;
end;
end;
a:=10000000; best:=i;
for k:=i to j do begin
b:=1;
for e:=2 to trunc(sqrt(k)) do if k mod e=0 then begin
b:=b+e+k div e;
end;
if sqr(trunc(sqrt(k)))=k then b:=b-trunc(sqrt(k));
b:=b/k;
if b<a then begin
a:=b; best:=k;
end;
end;
writeln(best);
end.
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※ 来源:·哈工大紫丁香 bbs.hit.edu.cn·[FROM: mtlab4.hit.edu.cn]