D. Shortest Cycle

D. Shortest Cycle

A[i]&A[j]!=0连边，

求图中最小环

N>128 时必有3环

其他暴力跑

folyd最小环

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define sc(x) scanf("%I64d",&x);
#define read(A) for(int i=0;i<n;i++) scanf("%I64d",&A[i]);
ll A[200005];
ll B[305][305];
ll dis[305][305];
ll N;
#define inf 1e18
ll floyd()
{
    ll MinCost = inf;
    for(int k=1; k<=N; k++)
    {
        for(int i=1; i<k; i++)
            for(int j=i+1; j<k; j++)
                MinCost = min(MinCost,dis[i][j]+B[i][k]+B[k][j]);
        for(int i=1; i<=N; i++)
            for(int j=1; j<=N; j++)
                dis[i][j]=min(dis[i][j],dis[i][k]+dis[k][j]);
    }
    if(MinCost==inf)return -1;
    else return MinCost;
}
 
int main()
{
    // ll N;
    sc(N);
    ll _k=1;
    for(int i=1; i<=N; i++)
    {
        sc(A[_k]);
        if(A[_k]!=0)_k++;
    }
    if(_k>=130)
    {
        puts("3");
    }
   
    else
    {
        N=_k-1;
        for(int i=1; i<=N; i++)
        {
            for(int j=1; j<=N; j++)
            {
                if(i!=j&&(A[i]&A[j]))
                {
                    B[i][j]=1;
                    dis[i][j]=1;
                }
                else if(i==j)
                {
                    B[i][j]=0;
                    dis[i][j]=0;
                }
                else
                {
                    B[i][j]=inf;
                    dis[i][j]=inf;
                }
            }
        }
        cout<<floyd()<<'\n';
 
    }
 
}