[interview_netease]九进制大数相加

思路：

这道题只a30+%，最后发现是小数0没处理，但此外其实忽略了最大的问题就是是个大数题目，长度在200位
错误版：巨坑1：c++字符串拼接不支持数字，而且字面值字符串拼接也要和string对象间隔才可以实现（记成了数值和string相间，在拼接字符串找错花了很多时间。。。python/java。。。）

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;

class Solution {
public:
    int decode(int n){
        int sum=0;
        int basic = 1;
        while (n>0) {
            int tempt = n % 10 * basic;
            sum += tempt;
            n = n / 10;
            basic = basic * 9;
        }
        return sum;
    }
    string encode(int n){
        stringstream ss;
        string result = "";
        while(n > 0){
            int tempt = n % 9;
            ss<<tempt<<result;/////////
            result = ss.str();
            n = n / 9;
            ss.str("");
        }
        return result;
    }
    string add(string num1, string num2) {
        string str_num1_int, str_num2_int, str_num1_flo, str_num2_flo;
        int pos1 = num1.find("."), pos2 = num2.find(".");
        str_num1_int = num1.substr(0, pos1);
        if(pos1 != -1)
            str_num1_flo = num1.substr(pos1+1, num1.size()-pos1-1);
        else
            str_num1_flo = "0";
        str_num2_int = num2.substr(0, pos2);
        if(pos2 != -1)
            str_num2_flo = num2.substr(pos2+1, num2.size()-pos2-1);
        else
            str_num2_flo = "0";
        int num1_int, num1_flo, num2_int, num2_flo;
        stringstream ss;
        ss<<str_num1_int;
        ss>>num1_int;
        ss.clear();
        ss<<str_num2_int;
        ss>>num2_int;
        ss.clear();
        ss<<str_num1_flo;
        ss>>num1_flo;
        ss.clear();
        ss<<str_num2_flo;
        ss>>num2_flo;
        ss.clear();

        cout<<num1_int<<" "<<num1_flo<<endl;
        cout<<num2_int<<" "<<num2_flo<<endl;
        string flo = encode(decode(num1_flo)+decode(num2_flo));
        int add=0;
        string integer;
        if(flo.size()>str_num1_flo.size() ||flo.size()>str_num2_flo.size()){
            ss<<flo[0];
            ss>>add;
            flo = flo.substr(1, flo.size()-1);
        }
        integer = encode(decode(num1_int) + decode(num2_int) + decode(add));
        cout<<integer<<" "<<flo;
        return integer + ((flo=="")?"":"."+flo);
    }
};

int main() {
    Solution s;
    cout<<s.add("1.5", "2.50");

    return 0;
}

大数相加版（发现以前对一些东西的印象会很大影响对其后续，敲了才发现大数相加也不过如此，以前老是觉得繁琐的像噩梦）

class Solution {
public:
    string add(string num1, string num2) {
        int pos1 = num1.find(".");
        int pos2 = num2.find(".");
        string n1_int = num1.substr(0, pos1);
        string n2_int = num2.substr(0, pos2);
        string n1_flo = ((pos1==-1)?"":num1.substr(pos1+1, num1.size()-1-pos1));
        string n2_flo = ((pos2==-1)?"":num2.substr(pos2+1, num2.size()-1-pos2));

        if(n1_flo.size()<n2_flo.size()){
            swap(n1_flo, n2_flo);
        }
        int i=n2_flo.size()-1;
        int in = 0;
        while(i>=0){
            int b = (n1_flo[i] + n2_flo[i] - 2*'0' + in)%9;
            in = (n1_flo[i] + n2_flo[i] - 2*'0' + in) / 9;
            n1_flo[i] = b + '0';
            i--;
        }

        if(n1_int.size()<n2_int.size()){
            swap(n1_int, n2_int);
        }
        i = 0;
        while(i<n2_int.size()){
            int b = (n1_int[n1_int.size()-1-i] + n2_int[n2_int.size()-1-i] - 2*'0' + in)%9;
            in = (n1_int[n1_int.size()-1-i] + n2_int[n2_int.size()-1-i] - 2*'0' + in) / 9;
            n1_int[i] = b + '0';
            i++;
        }


        i = n1_int.size()-i-1;
        while(i!=-1&&in){
            int b = (n1_int[i] - '0' + in) % 9;
            in = (n1_int[i] - '0' + in) / 9;
            i--;
        }
        if(i==-1&&in!=0){
            n1_int = to_string(in) + n1_int;
        }

        return n1_int + ((n1_flo.size()>0)?("."+n1_flo):"");
    }
};