Stringsobits chapter 3.2

跪跪跪,第三章没做几题,已经连跪几天了.好桑心,不过能咋办,不会就看别人的学啊.

同样是暴力搜,别人的剪枝实在是不能太叼.

 

  1 /*
  2 
  3 ID: hubiao cave
  4 
  5 PROG: kimbits
  6 
  7 LANG: C++
  8 
  9 */
 10 
 11 
 12 
 13 
 14 #include<iostream>
 15 
 16 #include<fstream>
 17 
 18 #include<string>
 19 
 20 using namespace std;
 21 
 22 
 23 
 24 int GetOne(int);
 25  unsigned int N,L,num;
 26 int main()
 27 
 28 {
 29 
 30     ifstream fin("kimbits.in");
 31     ofstream fout("kimbits.out");
 32     fin>>N>>L>>num;
 33     unsigned int counter=0;
 34     unsigned int bnum=0,left;
 35     unsigned int i=0;
 36     while(i<(unsigned int )1<<N)
 37     {
 38         
 39         bnum=GetOne(i);
 40         if(bnum<=L)
 41         {
 42             counter++;
 43         left=L-bnum;
 44         if(!(i&(1LL<<left)-1))
 45         {
 46         if(counter+(1LL<<left)-1<num)
 47         {
 48             counter+=(1LL<<left)-1;
 49             i+=(1LL<<left)-1;
 50         }
 51         else
 52         {
 53                 i=i+num-counter;
 54                 int p=N-1;
 55                 while(p>=0)
 56                 {
 57                 fout<<(i>>p&1);
 58                 p--;
 59                 }
 60                 fout<<endl;
 61                  return 0;
 62         }
 63         }
 64         }
 65         else
 66         {
 67             i+=(i&(i^(i-1)))-1;
 68         }
 69 
 70         if(counter==L)
 71         {
 72                 int p=N-1;
 73     while(p>=0)
 74     {
 75         fout<<(i>>p&1);
 76         p--;
 77     }
 78     fout<<endl;
 79     return 0;
 80 
 81         }
 82         i++;
 83     }
 84 
 85     int p=N-1;
 86     while(p>=0)
 87     {
 88         fout<<(i>>p&1);
 89         p--;
 90     }
 91     fout<<endl;
 92     return 0;
 93 
 94 
 95 }
 96 
 97 
 98 
 99 int GetOne(int i)
100 {
101     int counter=0;
102     while(i)
103     {
104         counter++;
105         i=i&(i-1);
106     }
107     return counter;
108 }

 

posted @ 2013-09-29 19:41  cavehubiao  阅读(124)  评论(0)  编辑  收藏  举报