43. Multiply Strings

class Solution {
    
vector<int> changeStringToVector(string num, vector<int> vector) {
    int length = num.length();
    for(int i = 0; i<length; i++){
        vector.push_back(num[i]-'0');
    }
    return vector;
}
public:
    string multiply(string num1, string num2) {
        int length1 = num1.length();
        int length2 = num2.length();
        // Create a vector containing integers
        std::vector<int> v_num1;
        std::vector<int> v_num2;
        string retString;

        v_num1 = changeStringToVector(num1, v_num1);
        v_num2 = changeStringToVector(num2, v_num2);
    
        // Iterate and print values of vector
        std::vector<int> finalNum;
        int finallength = length1+length2;
        finalNum.resize(finallength);
    
        for(int i = 0; i< length1; i++) {
           for(int j = 0; j< length2; j++) {
    
               finalNum[finallength-i-j-2] += v_num1[i]*v_num2[j];
               /*cout<<"v_num1 "<<v_num1[i] <<"  "<<"v_num2 "<<v_num2[j] <<endl
                   << finalNum[finallength-i-j-2] <<endl;*/
           }
        }
    
        for(int i = 0; i< finallength; i ++) {
            int a = finalNum[i]/10;
            int b = finalNum[i]%10;
            if(a) {
                finalNum[i] = b;
                finalNum[i+1] += a; 
            }
        }
        
        
        for(int i = finallength-1; i> 0; i--) {
            if (finalNum[i] == 0){
                finallength --;
            }
            else {
                break;
            }
        }

        for(int i = 0; i<finallength; i++) {
            cout<<"i =  "<<i<<"num is "<<finalNum[finallength-i-1]<<endl;
            retString.push_back(finalNum[finallength-i-1] +'0');
        }
        cout<<"string is "<<retString;
        return retString;
    }
    
};