int largestMatrix(vector<vector<int>> arr) {
    if (arr.size() == 0) return 0;
    int two_d[arr.size()][arr[0].size()];
    int maxNum = 0;
    for (int i = 0; i < arr.size(); i++){
        for (int x = 0; x < arr[0].size(); x++){
            if (arr[i][x] == 1){
                if (i == 0 || x == 0){
                    two_d[i][x] = 1;
                }else{
                    two_d[i][x] = min(min(two_d[i-1][x],two_d[i-1][x-1]),two_d[i][x-1]) +1;
                }
                if (two_d[i][x] > maxNum) maxNum = two_d[i][x];
            }else{
                two_d[i][x] = 0;
            }
        }
    }
    return maxNum;
}