听取WA声一片（悬关求助）

#include <bits/stdc++.h>
using namespace std;
struct Hugeint{
    int len,digits[32768];
    Hugeint(int x = 0){
        memset(digits,0,sizeof(digits));
        for(len = 1;x;len++){
            digits[len] = x%10;
            x/=10;
        }
        len--;
    }
    int &operator[](int i){
        return digits[i];
    }
    void carry(int l){
        len = l;
        for(int i=1;i<=len;i++){
            digits[i+1]+=digits[i]/10,digits[i]%=10;
        }
        for(;!digits[len];){
            len--;
        }
    }
    void output(){
        for(int i=max(len,1);i>=1;i--){
            printf("%d",digits[i]);
        }
    }
    Hugeint operator+(Hugeint num){
        Hugeint temp;
        len = max(num.len,len);
        for(int i=1;i<=len;i++){
            temp[i]+=num[i]+digits[i];
        }
        temp.carry(len+1);
        return temp;
    }
    Hugeint operator*(Hugeint num){
        Hugeint tmp;
        for(int i=1;i<=num.len;i++){
            for(int j=1;j<=len;j++){
                tmp[i+j] += num[i]*digits[j];
            }
        }
        int lent = num.len+len;
        tmp.carry(lent);
        for(;lent>=1&&!tmp[lent-1];){
            lent--;
        }
        tmp.len = lent;
        return tmp;
    }
};
string ca,cb;
Hugeint a,b,ans;
int main(){
    cin>>ca>>cb;
    for(int i=0;i<ca.size();i++){
        a[i+1] = ca[i]-'0';
    }
    for(int i=0;i<cb.size();i++){
        b[i+1] = cb[i]-'0';
    }
    (a*b).output();
}