UnitAreaOfLargestOne Samsung

#include <bits/stdc++.h>
using namespace std;
int a[500][500];
bool visited[500][500];
int len[500][500];
int rows, cols;
int X[8] = {-1,-1,-1,0,1,1,1,0};
int Y[8] = {-1,0,1,1,1,0,-1,-1};

struct s{
    int r, c;
};

bool valid(int r, int c) {
    if(r<rows && c<cols && r>=0 && c>=0)return true;
    return false;
}

int calculate(){
    int ans = 0;
    for(int i =0; i<rows; i++)for(int j =0; j<cols; j++)ans += len[i][j];
    return ans;
}

int solve(int r, int c){
    queue<s>q;
    s temp; temp.r = r; temp.c = c;
    q.push(temp);
    visited[r][c] = true; len[r][c] = 1;

    while(!q.empty()){
        s topp = q.front();
        int R = topp.r; int C = topp.c;
        q.pop();

        for(int i = 0; i<8; i++){
             int x = R + X[i]; int y = C + Y[i];
             if(valid(x,y))
             if(a[x][y] == 1 && visited[x][y] == false){
                 s temp1; temp1.r = x; temp1.c = y;
                 q.push(temp1);
                 len[x][y] = 1;
                 visited[x][y] = true;
             }
        }
    }
    return calculate();
}


int main() {
    int t; cin>>t;
    while(t--){
    int ans = 0;
    memset(visited, 0 , sizeof(visited));
    cin>>rows>>cols;

    for(int i =0; i<rows; i++)for(int j =0; j<cols; j++) cin>>a[i][j];

        for(int i =0; i<rows; i++){
            for(int j =0; j<cols; j++){
                if(a[i][j] == 1 && visited[i][j] == false){
                    memset(len, 0, sizeof(len));
                    ans = max( ans, solve(i,j) );
                }
            }
        }

        cout<<ans<<endl;
    }

    return 0;
}