File Question - C++

Given a text file with conversation write an algorithm which can give you list of user who chat the most

#include <iostream>
#include <fstream>
#include <string>
#include <unordered_map>
#include <algorithm>
#include <vector>

std::vector<std::string> getMostActiveUsers(const std::string& filePath) {
    std::unordered_map<std::string, int> userCounts;

    // Open the file
    std::ifstream file(filePath);
    if (!file.is_open()) {
        std::cerr << "Error: Unable to open file." << std::endl;
        return {};
    }

    // Read the file line by line
    std::string line;
    while (std::getline(file, line)) {
        // Extract user information
        std::string username …

algorithm chat conversation error file list question string text vector