先将整数部分和小数部分对齐，后面就跟高精度加法类似思路了，最后将末尾多余的零删除。

string sa,sb;

int main()
{
    int T;
    cin>>T;
    while(T--)
    {
        cin>>sa>>sb;

        int posa=sa.find('.'),posb=sb.find('.');
        int ra=sa.size()-posa,rb=sb.size()-posb;

        if(posa > posb) sb=string(posa-posb,'0')+sb;
        else sa=string(posb-posa,'0')+sa;

        if(ra > rb) sb=sb+string(ra-rb,'0');
        else sa=sa+string(rb-ra,'0');

        reverse(sa.begin(),sa.end());
        reverse(sb.begin(),sb.end());

        int carry=0;
        string res;
        for(int i=0;i<sa.size();i++)
        {
            if(sa[i] == '.')
            {
                res+='.';
                continue;
            }
            int t=(sa[i]-'0')+(sb[i]-'0')+carry;
            res+='0'+t%10;
            carry=t/10;
        }
        if(carry) res+='0'+carry;

        reverse(res.begin(),res.end());

        while(res[res.size()-1] == '0') res.erase(res.size()-1);

        cout<<res<<endl;
    }
    //system("pause");
    return 0;
}