[Usaco2007 Jan]Qualified Primes合格的素数

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[Usaco2007 Jan]Qualified Primes合格的素数

时间限制: 1 Sec 内存限制: 128 MB

题目描述

求A..B之间包含数字D的素数个数。(1<=A<=B<=4000000,B<=A+1000000)

输入

1行，三个整数A,B,D

输出

1个整数，满足条件的素数个数

样例输入

10 15 3

样例输出

var v:string; c,d:char; check:array[0..4000000]of boolean; prime:array[0..283146]of longint; i,j,t,n,a,b,x,y,ans:longint;begin readln(a,b,c,d); n:=b; for i:=2 to n do  check[i]:=true; check[1]:=false; for i:=2 to n do  begin   if check[i]=true   then    begin     inc(t);     prime[t]:=i;     if (i>=a)and(x=0)     then x:=t     else      if (i>b)and(y=0)      then y:=t-1;    end;   for j:=1 to t do    begin     if prime[j]*i>n     then break;     check[prime[j]*i]:=false;     if i mod prime[j]=0     then break;    end;  end; if y=0 then y:=t; {writeln(t); for i:=1 to t do  write(prime[i],' ');} for i:=x to y do  begin   str(prime[i],v);   for j:=1 to length(v) do    if v[j]=d    then     begin      inc(ans);      break;     end;  end; writeln(ans);end.

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