Submission

Score: 100

User: tull

Problemset: เกาะที่ใหญ่ที่สุด

Language: cpp

Time: 0.004 second

Submitted On: 2026-06-02 22:47:38

#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define bp '\n'
#define ld long double
#define vp cout<<'\n';
#define all(A) A.begin(),A.end()
using pii=pair<int,int>;
const int MOD=1e9+7;
const int MNLL=-1e18;
const int MXLL=1e18;
const int N=2e5+10;
const string sans[]={"NO","YES"};
signed main(){
    cin.tie(nullptr)->sync_with_stdio(false);
    int n,m;
    cin>>n>>m;
    vector<string>a(n);
    for(auto&e:a)cin>>e;
    vector<vector<int>>vst(n,vector<int>(m,0));
    pii dir[]={{1,0},{0,1},{-1,0},{0,-1}};
    auto BFS=[&](int i,int j){
        int cnt=0;
        queue<pii>q;
        q.emplace(i,j);
        while(!q.empty()){
            auto[i,j]=q.front();
            q.pop();
            if(vst[i][j])continue;
            vst[i][j]=1;
            ++cnt;
            for(auto&[f,s]:dir){
                int o=i+f,p=j+s;
                if(o<0 or o>=n or p<0 or p>=m or vst[o][p] or a[o][p]=='0')continue;
                q.emplace(o,p);
            }
        }
        return cnt;
    };
    int ans=0;
    for(int i=0;i<n;++i){
        for(int j=0;j<m;++j){
            if(a[i][j]=='0' or vst[i][j])continue;
            ans=max(ans,BFS(i,j));
        }
    }
    cout<<ans;
}