简单模拟二进制求和

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e3+5;
char a[maxn],s1[maxn],s2[maxn];
int main()
{
    scanf("%s",s1);
    scanf("%s",s2);
    int len1=strlen(s1);
    int len2=strlen(s2);
    if(len1<len2) swap(s1,s2);//s1保存较长串
    len1=strlen(s1);
    len2=strlen(s2);
    int add=0;
    len1--,len2--;
    while(len2>=0)
    {
        add+=s1[len1]-‘0‘+s2[len2]-‘0‘;
        a[len1]=add%2+‘0‘;
        add/=2;
        len1--,len2--;
    }
    while(add&&len1>=0)
    {
        add+=s1[len1]-‘0‘;
        a[len1]=add%2+‘0‘;
        add/=2;
        len1--;
    }
    if(add)//最后还有进位则后移加入进位即可
    {
        for(int i=strlen(a);i>0;i--)  a[i]=a[i-1];
        a[0]=add+‘0‘;
    }
    printf("%s\n",a);
    return 0;
}