Đề thi Toán - Tin trong nhà trường Bài 96

Bài 96/2002 - Số chung lớn nhất
(Dành cho học sinh THPT)
{$A+,B-,D+,E+,F-,G-,I+,L+,N-,O-,P-,Q+,R+,S+,T-,V+,X+}
{$M 16384,0,655360}
uses crt;
const maxn = 251;
 fi = 'string.inp';
 fo = 'string.out';
var pa : array[0..maxn,0..maxn] of byte;
 s1,s2,skq : string;
 max : byte;
procedure docf;
var f : text;
begin
 assign(f,fi);
 reset(f);
 readln(f,s1);
 read(f,s2);
 close(f);
end;
function maxso(a,b:byte) : byte;
begin
 maxso := (abs(a-b)+a+b) div 2;
end;
procedure Idonotknow;
var i,j : byte;
begin
 for i := length(s1) downto 1 do
 for j := length(s2) downto 1 do
 if s1[i] = s2[j] then pa[i,j] := pa[i+1,j+1] +1
 else pa[i,j] := maxso(pa[i+1,j] , pa[i,j+1] );
 max := pa[1,1];
end;
procedure wastingtime;
var ch : char;
 i,j,so,is,js : byte;
begin
 is := 1; js := 1;
 so := 0;
 repeat
 for ch := '9' downto '0' do
 begin
 i := is; j := js;
 while (s1[i] ch)and(i <= length(s1)) do inc(i);
 while (s2[j] ch)and(j <= length(s2)) do inc(j);
 if pa[i,j] = max - so then
 begin
 skq := skq + ch;
 is := i+1; js := j+1;
 break;
 end;
 end;
 inc(so);
 until max=so;
 while (skq[1] = '0')and(skq'0') do delete(skq,1,1);
end;
procedure ghif;
var f : text;
begin
 assign(f,fo);
 rewrite(f);
 if max = 0 then write(f,' Khong co xau chung !!!...')
 else
 begin
 wastingtime;
 write(f,skq);
 end;
 close(f);
end;
BEGIN
 docf;
 idonotknow;
 ghif;
END.