`DVSJROCQCVHTOJPUPKXP`
Answer: $15$
Your output: $16$
by Acoipp @ 2022-12-14 17:57:43
再来一组：
`IBKWZXKHXQVWFBLGHKLD`
Answer: $16$
Your output: $17$
by Acoipp @ 2022-12-14 17:58:42
谢谢
by Man_CCNU @ 2023-03-01 21:09:23
谢谢，我的也是这个思路，同80分，同被hack
by lupengheyyds @ 2023-03-16 16:49:37
所以是哪里逻辑不对呢？
这是我的代码，思路与楼主基本相同：
```
#include<bits/stdc++.h>
using namespace std;
string str;
int n;
long long dfs(int left,int right,char last){
if(right<left)return 0;
if(str[right]==last)return dfs(left,right-1,last);
if(str[left ]==last)return dfs(left+1,right,last);
for(int i=right;i>=left;i--)
if(str[i]==str[left])
return dfs(left,i-1,str[i])+dfs(i+1,right,last)+1;
return 0;
}
int main(){
cin>>str;
n=str.size();
str='\0'+str;
cout<<dfs(1,n,'a');
return 0;
}
```
by lupengheyyds @ 2023-03-16 16:51:27