Project: s41467-025-56893-9 | Function: adjmat2smiles (cpp)

system: You are an expert C++ programmer implementing algorithms from scientific papers.
Complete the masked function based on the algorithm description.
Follow C++ best practices and maintain consistent code style.
Return **only** the complete C++ function code.

user: Complete this C++ function:

**DESCRIPTION:** Converts adjacency matrices to SMILES notation for hydrocarbon molecules by reconstructing molecular bonds from graph representation

**KEY TERMS:** {
  "adjmat": "adjacency matrix representation",
  "num_atoms": "number of carbon atoms",
  "work_mol": "RDKit molecule object",
  "disconnect_smiles": "initial disconnected carbons",
  "atom_a/atom_b": "bonded atom pairs",
  "sanitizeMol": "fix valencies and hydrogens",
  "SMILES": "Simplified Molecular Input Line Entry System"
}

**CONTEXT CODE:** /*
    Author: Andreas Luttens
    Contact: andreas.luttens@gmail.com
    Date: June 22, 2023
    Description: Convert adjacency matrices into hydrocarbon SMILES
*/

// Basic utilities
#include <iostream>
#include <vector>
#include <string>

// RDKit functions
#include <GraphMol/GraphMol.h>
#include <GraphMol/FileParsers/MolSupplier.h>
#include <GraphMol/SmilesParse/SmilesWrite.h>
#include <GraphMol/SmilesParse/SmilesParse.h>
#include <GraphMol/FileParsers/FileParsers.h>

// Function to convert adjacency matrix to a SMILES
// Function to convert adjacency matrix to a SMILES
std::string adjmat2smiles(const std::vector<std::vector<unsigned int>> &adjmat)
{
    // Determine number of atoms in the molecule
    int num_atoms = adjmat.size();

    // Initialize a new molecule object
    ROMol::ROMol work_mol(num_atoms);

    // Add atoms to the molecule
    for (int i = 0; i < num_atoms; i++) 
    {
        work_mol[i].SetAtomicNum(6); // Carbon
        work_mol[i].AddDegree(4); // Tetravalent carbons by default
    }

    // Reconstruct molecular bonds
    for (int atom_a = 0; atom_a < num_atoms; atom_a++) 
    {
        for (int atom_b = atom_a + 1; atom_b < num_atoms; atom_b++) 
        {
            if (adjmat[atom_a][atom_b] > 0) 
            {
                work_mol.GetBondWithIdx(work_mol.AddBond(atom_a, atom_b, static_cast<ROMol::Bond::BondType>(adjmat[atom_a][atom_b]))) -> SetIsAromatic(false);
            }
        }
    }

    // Initialize disconnected carbons SMILES
    std::string disconnect_smiles;
    for (int i = 0; i < num_atoms; i++) 
    {
        disconnect_smiles += "C";
    }

    // Sanitize the molecule (fix valencies and hydrogens)
    try 
    {
        sanitizeMol(work_mol);
    } 
    catch (const std::exception &e) 
    {
        std::cerr << "Error during molecule sanitization: " << e.what() << std::endl;
        return disconnect_smiles; // Return disconnected carbons SMILES if sanitization fails
    }

    // Convert the molecule to SMILES
    return MolToSmiles(work_mol);
}

// Driver function
int main(int argc, char* argv[]) 
{    
    // File names
    std::string out_file_path;

    // Argument parser
    int opt;
    while ((opt = getopt(argc, argv, "o:h")) != -1) 
    {
        switch (opt) 
        {
            case 'o':
                out_file_path = optarg;
                break;
            case 'h':
                std::cout << "Usage: " << argv[0] << "-o <output_file_path>" << std::endl;
                return 0;
            default:
                std::cerr << "Usage: " << argv[0] << "-o <output_file_path>" << std::endl;
                return 1;
        }
    }

    // Verify path
    if (out_file_path.empty()) 
    {
        std::cerr << "Error: Output file path not provided. Use the -o option." << std::endl;
        std::cout << "Usage: " << argv[0] << "-o <output_file_path>" << std::endl;
        return 1;
    }

    // Verify you can open output file
    std::ofstream output_file(out_file_path);
    if (!output_file) 
    {
        std::cerr << "Error opening file." << std::endl;
        return 1;
    }

    // String to store a line from the input file
    std::string line;

    // Placeholder for an adjancency matrix
    std::vector<std::vector<unsigned int>> adjmat;

    //
    bool grow = false;

    // Read the input file line by line
    while (std::getline(std::cin, line)) 


Complete the function implementation replacing "throw std::runtime_error("Not implemented");".