[SGU]111. Very simple problem

Analysis

    不要被标题迷惑了！没那么看上去简单哟！刚看这题总觉得似曾相识，复习初赛的时候才发现是去年初赛完善程序的第一题……不过把那个程序交上去应当是会TLE的吧……因为它没压位……我的AC程序是二分+压位高精。据说还有笔算开方的算法，我果然小学数学没学好T T……

Accepted Code

var    a,l,r,mid,sqrmid,tmp:array[0..1100] of int64;    lens,lenl,lenr,lenmid,lensqrmid,i,j:longint;    s:ansistring;    bo1,bo2:boolean;function comp:boolean;var    bo:boolean;    i:longint;begin    if not bo2 then    begin        tmp:=l;        inc(tmp[1]);        i:=1;        while tmp[i]>99999999 do        begin            inc(tmp[i+1]);            dec(tmp[i],100000000);            inc(i);        end;        bo2:=true;    end;    bo:=true;    for i:=1 to lenr do    begin        bo:=bo and (r[i]=tmp[i]);        if not bo then            break;    end;    comp:=bo;end;procedure calcsqrmid;var    i,j:longint;begin    fillchar(sqrmid,sizeof(sqrmid),0);    for i:=1 to lenmid do        for j:=1 to lenmid do            sqrmid[i+j-1]:=sqrmid[i+j-1]+mid[i]*mid[j];    lensqrmid:=lenmid shl 1;    for i:=1 to lensqrmid do    begin        sqrmid[i+1]:=sqrmid[i+1]+sqrmid[i] div 100000000;        sqrmid[i]:=sqrmid[i] mod 100000000;    end;    if sqrmid[lensqrmid]=0 then        dec(lensqrmid);end;begin    readln(s);    lens:=length(s) div 8;    if length(s) mod 8<>0 then        inc(lens);    i:=1;    while lens>i do    begin        val(copy(s,length(s)-7,length(s)),a[i],lenl);        delete(s,length(s)-7,8);        inc(i);    end;    val(s,a[i],lenl);    fillchar(l,sizeof(l),0);    l[1]:=1;    lenl:=1;    fillchar(r,sizeof(r),0);    r[131]:=1;    lenr:=131;    bo2:=false;    repeat        fillchar(mid,sizeof(mid),0);        for i:=1 to lenr do        begin            mid[i]:=mid[i]+l[i]+r[i];            if mid[i]>=100000000 then            begin                mid[i]:=mid[i]-100000000;                mid[i+1]:=1;            end;        end;        if mid[lenr+1]>0 then            lenmid:=lenr+1        else            lenmid:=lenr;        for i:=lenmid downto 1 do        begin            if mid[i] and 1>0 then                inc(mid[i-1],100000000);            mid[i]:=mid[i] shr 1;        end;        if mid[lenmid]=0 then            dec(lenmid);        if (lenmid*2<lens) or (lenmid*2-1>lens) then            bo1:=lenmid*2-1>lens        else        begin            calcsqrmid;            if lensqrmid<>lens then                bo1:=lensqrmid>lens            else            begin                i:=lens;                while (i>0) and (sqrmid[i]=a[i]) do                    dec(i);                bo1:=sqrmid[i]>a[i];            end;        end;        if bo1 then        begin            r:=mid;            lenr:=lenmid;        end        else        begin            l:=mid;            lenl:=lenmid;            bo2:=false;        end;        if lenl+1<lenr then            continue;    until comp();    write(l[lenl]);    for i:=lenl-1 downto 1 do    begin        str(l[i],s);        while length(s)<8 do            s:='0'+s;        write(s);    end;    writeln;end.