NOI2002 荒岛野人

这题其实黑书上有，只是我脑残的没想起来……

其实就是拓展欧几里得算法

我参看的题解：http://www.cnblogs.com/Rinyo/archive/2012/11/25/2788373.html

还有一个讲解的很清楚的exgcd：http://www.cnblogs.com/Rinyo/archive/2012/11/25/2787419.html

代码：

var c,p,l:array[0..50] of longint;
    ans,now,n,i,j,d,x,y,pp,cc:longint;
    flag:boolean;
function min(x,y:longint):longint;
 begin
 if x<y then exit(x) else exit(y);
 end;
function max(x,y:longint):longint;
 begin
 if x>y then exit(x) else exit(y);
 end;
function exgcd(a,b:longint;var x,y:longint):longint;
 var t,d:longint;
 begin
 if b=0 then
  begin
  x:=1;y:=0;exit(a);
  end;
 d:=exgcd(b,a mod b,x,y);
 t:=x;x:=y;y:=t-(a div b)*y;
 exit(d);
 end;
procedure main;
 begin
 readln(n);
 for i:=1 to n do
  begin
  readln(c[i],p[i],l[i]);
  ans:=max(ans,c[i]);
  end;
 while true do
  begin
  flag:=true;
  for i:=1 to n-1 do
   begin
    for j:=i+1 to n do
     begin
     pp:=p[i]-p[j];cc:=c[j]-c[i];
     d:=exgcd(pp,ans,x,y);
     if cc mod d<>0 then continue;
     now:=x*cc div d;
     now:=now mod (ans div d);
     if now<0 then inc(now,abs(ans div d));
     if now<=min(l[i],l[j]) then begin flag:=false;break;end;
     end;
    if not(flag) then break;
    end;
  if flag then break;
  inc(ans);
  end;
 writeln(ans);
 end;
begin
 main;
end.                         

我要开始刷noi历年题了！我相信我一定能够坚持下来！