为啥90分，另外如果说两个字符串形如这样abcd abcda这该怎么弄？
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <stack>
#include <string>
#include <queue>
#define N 2005
using namespace std;
string s1,s2;
int b[400];
int main() {
cin>>s1>>s2;
for(int i=0;;++i){
if(s1[i]!=s2[i]){
cout<<s2[i]<<s1[i];
b[s1[i]]=b[s2[i]]=1;
break;
}
}
for(char i='a';i<='z';++i){
if(!b[i])
cout<<i;
}
return 0;
}
