hdu1286

刚开始用了几次gcd(),结果n次tle, 最后用了筛选法，终于a了，效率提高不少啊！

http://acm.hdu.edu.cn/showproblem.php?pid=1286

View Code

   
     

    
      #include
    
      "
    
      iostream
    
      "
    
      

    
      using
    
       
    
      namespace
    
       std;

    
      int
    
       main()
{
 
    
      int
    
       n,a,i,j,count;
 
    
      int
    
       b[
    
      32768
    
      ];
 cin
    
      >>
    
      n;
 
    
      while
    
      (n
    
      --
    
      )
 {
 cin
    
      >>
    
      a;
 memset(b,
    
      0
    
      ,
    
      sizeof
    
      (b));
 
    
      for
    
      (i
    
      =
    
      2
    
      ;i
    
      <=
    
      a;i
    
      ++
    
      )
 {
 
    
      if
    
      (a
    
      %
    
      i
    
      ==
    
      0
    
      &&
    
      b[i]
    
      ==
    
      0
    
      )
 {
 
    
      for
    
      (j
    
      =
    
      i;j
    
      <=
    
      a;j
    
      +=
    
      i)
 {
 b[j]
    
      =
    
      1
    
      ;
 }
 }
 }
 count
    
      =
    
      0
    
      ;
 
    
      for
    
      (i
    
      =
    
      1
    
      ;i
    
      <
    
      a;i
    
      ++
    
      )
 {
 
    
      if
    
      (b[i]
    
      ==
    
      0
    
      ) count
    
      ++
    
      ;
 }
 cout
    
      <<
    
      count
    
      <<
    
      endl;
 }
 
    
      return
    
       
    
      0
    
      ;

    
      }