华为练习题系列---超长整数相加

#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
  string addend;
  string augend;
  string ret;
  while (cin >> addend >> augend)
  {
    int sign = 0;//进位标志
    while (1)
    {
      //将两个字符串补齐为等长字符串
      if (addend.size() < augend.size())
      {
        addend = '0' + addend;
      }
      else if (addend.size() > augend.size())
      {
        augend = '0' + augend;
      }
      else
      {
        break;
      }
    }
    int len = addend.size();
    vector<char> ret(len + 1);//保存结果
    int sum = 0;//每位求和结果
    int result = 0;//
    for (int i = len - 1; i > -1; i--)
    {
      int temp1 = addend[i] - '0';//字符转换位数字
      int temp2 = augend[i] - '0';
      sum = sign + temp1 + temp2;
      result = sum % 10;
      sign = sum / 10;
      ret[i + 1] = result + '0';
      if (i == 0)//考虑最高位有进位
      {
        if (sign == 1)
        {
          ret[i] = 1;
        }
        else
        {
          ret[i] = 0;
        }
      }
    }
    if (ret[0] == 1)
    {
      cout << '1';
    }
    for (int i = 1; i < len + 1; i++)
    {
      cout << ret[i];
    }
    cout << endl;
  }
  return 0;
}