[WF2012]infiltration

[WF2012]infiltration

完全图

最多选择logn个点（下取整）（每选择一个点覆盖至少一半的规模）

暴力O(75^5)（不严格）枚举+bitset

（随机化也可过）

#include<bits/stdc++.h>
#define reg register int
#define il inline
#define int long long
#define numb (ch^'0')
using namespace std;
typedef long long ll;
il void rd(ll &x){
    char ch;x=;bool fl=false;
    while(!isdigit(ch=getchar()))(ch=='-')&&(fl=true);
    for(x=numb;isdigit(ch=getchar());x=x*+numb);
    (fl==true)&&(x=-x);
}
namespace Miracle{
const int N=;
int n;
char con[N][N];
bitset<N>to[N],now;
bool c1(){
    for(reg a1=;a1<=n;++a1)
        if(to[a1].count()==n) return true;
    return false;
}
bool c2(){
    for(reg a1=;a1<=n;++a1)
    for(reg a2=a1+;a2<=n;++a2)
        if((to[a1]|to[a2]).count()==n) return true;
    return false;
}
bool c3(){
    for(reg a1=;a1<=n;++a1)
    for(reg a2=a1+;a2<=n;++a2)
    for(reg a3=a2+;a3<=n;++a3)
        if((to[a1]|to[a2]|to[a3]).count()==n) return true;
    return false;
}
bool c4(){
    for(reg a1=;a1<=n;++a1)
    for(reg a2=a1+;a2<=n;++a2)
    for(reg a3=a2+;a3<=n;++a3)
    for(reg a4=a3+;a4<=n;++a4)
        if((to[a1]|to[a2]|to[a3]|to[a4]).count()==n) return true;
    return false;
}
bool c5(){
    for(reg a1=;a1<=n;++a1)
    for(reg a2=a1+;a2<=n;++a2)
    for(reg a3=a2+;a3<=n;++a3)
    for(reg a4=a3+;a4<=n;++a4)
    for(reg a5=a4+;a5<=n;++a5)
        if((to[a1]|to[a2]|to[a3]|to[a4]|to[a5]).count()==n) return true;
    return false;
}
int main(){
    int o=;
    while(scanf("%d",&n)!=EOF){
        for(reg i=;i<=n;++i) to[i].reset();
        for(reg i=;i<=n;++i){
            scanf("%s",con[i]+);
            for(reg j=;j<=n;++j){
                if(i==j) continue;
                if(con[i][j]=='')to[i][j]=;
                else to[i][j]=;
            }
            to[i][i]=;
        }
        int ans=;
        if(c1()) ans=;
        else if(c2()) ans=;
        else if(c3()) ans=;
        else if(c4()) ans=;
        else if(c5()) ans=;
        else ans=;
        printf("Case %d: %d\n",++o,ans);
    }
    return ;
}

}
signed main(){
    Miracle::main();
    return ;
}

/*
   Author: *Miracle*
   Date: 2019/2/26 18:48:55
*/