把大数分成两个数的简单方法？c++

#include <iostream>
#include <cmath>

int main() {
    long long num = 1234567890123456789;
    long long half = num / 2;

    std::cout << "Original number: " << num << std::endl;
    std::cout << "First part: " << half << std::endl;
    std::cout << "Second part: " << num - half << std::endl;

    return 0;
}

#include <iostream>
#include <cmath>

int main() {
    long long num = 1234567890123456789;
    int numDigits = std::to_string(num).length();
    long long divisor = std::pow(10, numDigits / 2);

    long long firstPart = num / divisor;
    long long secondPart = num % divisor;

    std::cout << "Original number: " << num << std::endl;
    std::cout << "First part: " << firstPart << std::endl;
    std::cout << "Second part: " << secondPart << std::endl;

    return 0;
}

#include <iostream>
#include <cstdlib>
#include <ctime>

int main() {
    long long num = 1234567890123456789;
    srand(time(0));

    long long randomPart = rand() % num;
    long long otherPart = num - randomPart;

    std::cout << "Original number: " << num << std::endl;
    std::cout << "First part: " << randomPart << std::endl;
    std::cout << "Second part: " << otherPart << std::endl;

    return 0;
}

#include <iostream>
#include <random>

int main() {
    long long num = 1234567890123456789;
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<long long> dis(0, num);

    long long randomPart = dis(gen);
    long long otherPart = num - randomPart;

    std::cout << "Original number: " << num << std::endl;
    std::cout << "First part: " << randomPart << std::endl;
    std::cout << "Second part: " << otherPart << std::endl;

    return 0;
}