题解 | #高精度整数加法#

少写一种情况！爷爷

#include<bits/stdc++.h>
using namespace std;
int main(void)
{
    string str1,str2;
    int temp = 0;
    cin>>str1>>str2;
    int size =str1.size();
    int size2 = str2.size();
    if(size>size2)
    {
        for(int i=0;i<size2;i++)
        {
            if(temp>=10)
            temp = (int)(str1[size-1-i]-'0') +(int)(str2[size2-1-i]-'0') +1;
            else
                temp = (int)(str1[size-1-i]-'0') +(int)(str2[size2-1-i]-'0') ;
            str1[size-1-i] = temp%10 +'0';
        }
        if(temp>=10)
            str1[size-1-size2] = (int)(str1[size-1-size2])+1;
        cout<<str1;
    }
    if(size == size2)
    {
        for(int i=0;i<size2;i++)
        {
            if(temp>=10)
            temp = (int)(str1[size-1-i]-'0') +(int)(str2[size2-1-i]-'0') +1;
            else
                temp = (int)(str1[size-1-i]-'0') +(int)(str2[size2-1-i]-'0') ;
            str1[size-1-i] = temp%10 +'0';
        }
        if(temp>=10)
            str1.insert(str1.begin(),'1');
        cout<<str1;
    }
    else if(size<size2)
    {
        for(int i=0;i<size;i++)
        {
            if(temp>=10)
            temp = (int)(str2[size2-1-i]-'0') +(int)(str1[size-1-i]-'0') +1;
            else
                temp = (int)(str2[size2-1-i]-'0') +(int)(str1[size-1-i]-'0') ;
            str2[size2-1-i] = temp%10 +'0';
        }
        if(temp>=10)
            if(str2[size2-1-size]-'0'<9)
            str2[size2-1-size] = (int)(str2[size2-1-size])+1;
            else if(str2[size2-1-size]-'0'==9)
            {
                str2[size2-1-size] = '0';
                str2[size2-2-size] = (int)(str2[size2-2-size])+1;
            }
            
        cout<<str2;
    }
}