【解決方法】最大公約数 (GCD) を見つける方法

C++ についてサポートが必要です。
最大公約数を見つける 𝑔𝑐𝑑⁡(𝑎,𝑏) 2 つの正の整数の間 𝑎 そして 𝑏。
例：

a = 20230925 b = 52903202
a = 111111222222333333444444555555 b = 666666777777888888999999

コードは Visual Studio の Linux および Windows 上で動作するはずですが、エラーが発生します。

私が試したこと:

#include <iostream>
#include <string>
#include <vector>

int num_cmp(const std::vector<int>& num1, const std::vector<int>& num2){
    std::cout << "num_cmp\n";
    /* function comparing two numbers whose digits are stored in vectors
    return -1 if smaller, 1 if larger, and 0 if equal */

    // compare number of digits first
    int len1 = num1.size(), len2 = num2.size();
    int msb = 0;
    while (num1[msb] == 0){  // skip zeros
        -- len1;
        ++ msb;
    }
    msb = 0;
    while (num2[msb] == 0){  // skip zeros
        -- len2;
        ++ msb;
    }
    if (len1 > len2)
        return 1;
    else if (len1 < len2)
        return -1;
    else {
        // if same length, compare digit by digit
        for (int i = 0; i < len1; ++i){
            if (num1[i] > num2[i])
                return 1;
            else if (num1[i] < num2[i])
                return -1;
        }
    }
    return 0;
}

void vec_intfromchar(std::vector<int>& a, const std::vector<char>& num) {
	/* convert char vector to int vector
	 two vectors are assumed to have the same size  */
	a.resize(num.size()); // Asegura que a tenga el mismo tamaño que num
	for (int i = 0; i < a.size(); ++i)
		a[i] = num[i] - '0';
	return;
}

void print_vec(std::vector<int>& a){
    int start = 0;
    while (start < a.size() && a[start ++] == 0); // skip zeros
    for (int i = start - 1; i < a.size(); ++i)
        std::cout << a[i];
    std::cout << "\n";

    return;
}

bool is_even(std::vector<int>& a){
    std::cout << "is_even\n";
    return a[a.size() - 1] % 2 == 0;
}

bool is_zero(std::vector<int>& a){
    std::cout << "is_zero\n";
    for (int i = 0; i < a.size(); ++i)
        if (a[i] != 0)
            return false;
    return true;
}

void substract(std::vector<int>& b, std::vector<int>& a){
    std::cout << "============ subtract =============\n";
    // b = b - a
    while (a.size() < b.size())
        a.insert(a.begin(), 0); // sign extension
    while (a.size() > b.size())
        b.insert(b.begin(), 0); // sign extension
    print_vec(a);
    print_vec(b);

    for (int i = b.size() - 1; i >= 0; --i){
        // std::cout << "b[" << i << "]: " << b[i] << ", a[" << i << "]: " << a[i] << "\n";
        if (b[i] < a[i]){
            b[i] = b[i] - a[i] + 10;
            -- b[i - 1];  // borrow
        }
        else
            b[i] -= a[i];
    }
    return;
}

void divide_by2(std::vector<int>& a) {
	std::cout << "divide_by2\n";
	int dividend = 0;
	for (int i = 0; i < a.size(); ++i) {
		dividend = dividend * 10 + a[i];
		a[i] = dividend / 2;
		dividend %= 2;
	}
    return;
}

void multiply_by2(std::vector<int>& a){
    std::cout << "multiply_by2\n";
    int mult = 0, carry = 0;
    for (int i = a.size() - 1; i >= 0; --i){
        mult = a[i] * 2 + carry;
        carry = mult / 10;
        a[i] = mult % 10;
    }
    return;
}

void addition(std::vector<int>& a, std::vector<int>& b){
    std::cout << "addtion\n";
    // a = a + b

    while (a.size() < b.size())
        a.insert(a.begin(), 0); // sign extension
    while (b.size() < a.size())
        b.insert(b.begin(), 0); // sign extension

    int add = 0, carry = 0;
    for (int i = a.size() - 1; i >= 0; --i){
        add = a[i] + b[i] + carry;
        carry = add / 10;
        a[i] = add % 10;
    }
    return;
}

std::vector<int> multiply(std::vector<int>& a, std::vector<int>& b){
    std::cout << "multiply\n";

    std::vector<int> acc(a.size() + b.size(), 0); // the final result

    for (int i = b.size() - 1; i >= 0; --i){
        int mult = 0, carry = 0;
        std::vector<int> result(a.size() + 1, 0);   // middle result

        for (int j = a.size() - 1; j >= 0; --j){
            mult = a[j] * b[i] + carry;
            carry = mult / 10;
            // std::cout << "mult: " << mult << "\n";
            // std::cout << "carry: " << carry << "\n";
            result[j + 1] = mult % 10;
            if (j == 0)
                result[0] = carry;
        }

        // std::cout << "result: ";
         print_vec(result);

        // append zeros to the oprand
        for (int k = i + 1; k < b.size(); ++k)
            result.insert(result.end(), 0);
        // std::cout << "result after appending: ";
         print_vec(result);

        // acumulation
        addition(acc, result);
        // std::cout << "acc: ";
         print_vec(acc);
    }
    return acc;
}

int main(){
    std::string str1, str2;
    std::cin >> str1 >> str2;
    std::vector<char> num1(str1.begin(), str1.end());
    std::vector<char> num2(str2.begin(), str2.end());
    
    // initial values for a, b, and ans
    std::vector<int> ans(1, 1);
    std::vector<int> a(num1.size());
    std::vector<int> b(num2.size());
    vec_intfromchar(a, num1);
    vec_intfromchar(b, num2);

    // std::cout << num_cmp(a, b) << "\n";
    if (num_cmp(a, b) != -1)
        a.swap(b);  // set a to be the smaller one
    
    // Binary Algorithm for gcd
    while (!is_zero(a) && !is_zero(b)){
        if (is_even(a) && is_even(b)) {
            multiply_by2(ans);
            divide_by2(a);
            divide_by2(b);
        } else if (is_even(a)) {
            divide_by2(a);
        } else if (is_even(b)) {
            divide_by2(b);
        }

        if (num_cmp(a, b) == 1)  // a > b
            a.swap(b);
        substract(b, a);    // b = b - a
    }
    std::vector<int> gcd = multiply(a, ans);
  /*  print_vec(gcd);*/

    return 0;
}