Submission #60284935

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Source Code Expand

#include<bits/stdc++.h>
#include"atcoder/all"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(a) a.begin(),a.end()
typedef long long ll;
typedef vector<ll> vi;
typedef pair<ll,ll> P;
const ll mod=1000000007;
const ll inf=1ll<<61;
typedef modint998244353 mi;

int h,w;
string s[16];
int used[16][16];
int dx[]={0,1,0,-1},dy[]={1,0,-1,0};

void dfs(int ni,int nj,int &ans,int cnt=1){
	rep(i,4){
		int mi=ni+dx[i],mj=nj+dy[i];
		if(0<=mi&&mi<h&&0<=mj&&mj<w&&s[mi][mj]!='#'){
			if(used[mi][mj]==0){
				used[mi][mj]=1;
				dfs(mi,mj,ans,cnt+1);
				used[mi][mj]=0;
			}
			else if(used[mi][mj]==2&&cnt>=3){
				ans=max(ans,cnt);
			}
		}
	}
	return;
}

int main(){
	cin>>h>>w;
	rep(i,h)cin>>s[i];

	int ans=-1;

	rep(i,h){
		rep(j,w){
			if(s[i][j]=='#')continue;
			rep(ii,h)rep(jj,w)used[ii][jj]=0;
			used[i][j]=2;
			dfs(i,j,ans);
		}
	}

	cout<<ans<<endl;
}

Submission Info

Judge Result