【BZOJ2982】combination（Lucas定理）

题意：求C(n,m)

n,m<=200000000

思路：c(n,m)=c(n mod mo,m mod mo)*c(n div mo,m div mo) mod mo (n>=mo或m>=mo)

c(x,y)=0 (x<y)

c(n,m)=fac[n]*exf[m]*exf[n-m] (n,m<mo)

 const mo=;
 var exf,fac:array[..]of longint;
     n,i,x,y:longint;

 function c(n,m:longint):longint;
 begin
  if n<m then exit();
  if (n<mo)and(m<mo) then exit(fac[n]*exf[m] mod mo*exf[n-m] mod mo);
  exit(c(n mod mo,m mod mo)*c(n div mo,m div mo) mod mo);
 end;

 begin
  assign(input,'bzoj2982.in'); reset(input);
  assign(output,'bzoj2982.out'); rewrite(output);
  readln(n);
  exf[]:=; exf[]:=; fac[]:=; fac[]:=;
  for i:= to  do
  begin
   exf[i]:=exf[mo mod i]*(mo-mo div i) mod mo;
   fac[i]:=fac[i-]*i mod mo;
  end;
  for i:= to  do exf[i]:=exf[i-]*exf[i] mod mo;

  for i:= to n do
  begin
   readln(x,y);
   writeln(c(x,y));
  end;
  close(input);
  close(output);
 end.