bzoj 1002 找规律（基尔霍夫矩阵）

　　网上说的是什么基尔霍夫矩阵，没学过这个，打个表找下规律，发现

w[i]=3*w[i-1]-w[i-2]+2;

然后写个高精直接递推就行了

//By BLADEVIL
var
    n                    :longint;
    a, b, c                :array[..] of longint;
    w                    :array[..] of ansistring;
    i                    :longint;

function plus(s1,s2:ansistring):ansistring;
var
    len                    :longint;
    i                    :longint;
    s                    :ansistring;

begin
    fillchar(a,sizeof(a),);
    fillchar(b,sizeof(b),);
    fillchar(c,sizeof(c),);
    len:=length(s1);
    for i:= to len do a[(len-i) div +]:=a[(len-i) div +]*+ord(s1[i])-;
    len:=length(s2);
    for i:= to len do b[(len-i) div +]:=b[(len-i) div +]*+ord(s2[i])-;
    if length(s1)>len then len:=length(s1);
    len:=(len+) div ;
    for i:= to len do
    begin
        c[i]:=c[i]+a[i]+b[i];
        c[i+]:=c[i+]+c[i] div ;
        c[i]:=c[i] mod ;
    end;
    inc(len);
    plus:='';
    for i:=len downto  do
    begin
        str(c[i],s);
        if c[i]< then plus:=plus+'';
        if c[i]< then plus:=plus+'';
        if c[i]< then plus:=plus+'';
        plus:=plus+s;
    end;
    while (plus[]='') and (length(plus)>) do delete(plus,,);
end;

function jian(s1,s2:ansistring):ansistring;
var
    len                    :longint;
    i                    :longint;
    s                    :ansistring;
begin
    fillchar(a,sizeof(a),);
    fillchar(b,sizeof(b),);
    fillchar(c,sizeof(c),);
    len:=length(s1);
    for i:= to len do a[(len-i) div +]:=a[(len-i) div +]*+ord(s1[i])-;
    len:=length(s2);
    for i:= to len do b[(len-i) div +]:=b[(len-i) div +]*+ord(s2[i])-;
    len:=(length(s1)+) div ;
    for i:= to len do c[i]:=a[i]-b[i];
    for i:= to len do if c[i]< then
    begin
        c[i]:=c[i]+;
        dec(c[i+]);
    end;
    jian:='';
    for i:=len downto  do
    begin
        str(c[i],s);
        if c[i]< then jian:=jian+'';
        if c[i]< then jian:=jian+'';
        if c[i]< then jian:=jian+'';
        jian:=jian+s;
    end;
    while (jian[]='') and (length(jian)>) do delete(jian,,);
end;

begin
    read(n);
    w[]:=''; w[]:='';
    for i:= to n do
        w[i]:=plus(jian(plus(plus(w[i-],w[i-]),w[i-]),w[i-]),'');
    writeln(w[n]);
end.