【JZOJ4857】Tourist Attractions（Bitset）

 1 #include<map>
 2 #include<set>
 3 #include<cmath>
 4 #include<cstdio>
 5 #include<vector>
 6 #include<cstring>
 7 #include<cstdlib>
 8 #include<iostream>
 9 #include<algorithm>
10 #include<bitset>
11 #define MAXN 1510
12 #define MAXM 4100000
13 using namespace std;
14 
15 typedef long long ll;
16 bitset<MAXN> a[MAXN],tmp;
17 
18 int head[MAXM],vet[MAXM],next[MAXM],n,i,j,tot;
19 ll size[MAXN];
20 ll ans;
21 
22 void add(int a,int b)
23 {
24   next[++tot]=head[a];
25   vet[tot]=b;
26   head[a]=tot;
27 }
28 
29 int main()
30 {
31     //freopen("jzoj4857.in","r",stdin);
32     //freopen("jzoj4857.out","w",stdout);
33     scanf("%d",&n);
34     for(int i=1;i<=n;i++)
35     {
36         scanf("\n");
37         for(int j=1;j<=n;j++) 
38         {
39             char ch;
40             scanf("%c",&ch);
41             if(ch==‘1‘)
42              {
43                 add(i,j);
44                 size[i]++;
45                 a[i][j]=1;
46              }
47                 
48         }
49     }
50     for(int i=1;i<=n;i++)
51      for(int e=head[i];e;e=next[e])
52      {
53          int v=vet[e];
54          ans+=(size[i]-1)*(size[v]-1);
55          tmp=a[i]&a[v];
56          ans-=tmp.count();
57      }
58      printf("%lld\n",ans);
59      return 0;
60 }