将大数字乘以数组C++

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

using namespace std;

string multiply(string num, vector<int>& arr) {
    int n = num.size();
    int m = arr.size();
    vector<int> result(n + m, 0);

    for (int i = n - 1; i >= 0; i--) {
        for (int j = m - 1; j >= 0; j--) {
            int mul = (num[i] - '0') * arr[j];
            int sum = result[i + j + 1] + mul;
            result[i + j + 1] = sum % 10;
            result[i + j] += sum / 10;
        }
    }

    // 处理进位
    for (int i = n + m - 1; i > 0; i--) {
        result[i - 1] += result[i] / 10;
        result[i] %= 10;
    }

    // 转换为字符串
    string res = "";
    int i = 0;
    while (i < n + m && result[i] == 0) {
        i++;
    }
    for (; i < n + m; i++) {
        res += to_string(result[i]);
    }

    return res;
}

int main() {
    string num = "123456789";
    vector<int> arr = {1, 2, 3};

    string result = multiply(num, arr);
    cout << "Result: " << result << endl;

    return 0;
}