BZOJ2008 JSOI2010连通数（floyd+bitset）

#include<iostream> 
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<bitset>
using namespace std;
int read()
{
    int x=0,f=1;char c=getchar();
    while (c<‘0‘||c>‘9‘) {if (c==‘-‘) f=-1;c=getchar();}
    while (c>=‘0‘&&c<=‘9‘) x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return x*f;
}
#define N 2010
int n,ans=0;
bitset<N> a[N];
int main()
{
    freopen("bzoj2208.in","r",stdin);
    freopen("bzoj2208.out","w",stdout);
    n=read();
    for (int i=1;i<=n;i++)
    {
        char c=getchar();
        while (c!=‘0‘&&c!=‘1‘) c=getchar();
        for (int j=1;j<=n;j++)
        a[i][j]=c^48,c=getchar();
        a[i][i]=1;
    }
    for (int k=1;k<=n;k++)
        for (int i=1;i<=n;i++)
        if (a[i][k]) a[i]|=a[k];
    for (int i=1;i<=n;i++) ans+=a[i].count();
    cout<<ans;
    fclose(stdin);fclose(stdout);
    return 0;
}