67分求调

#include<iostream>
#include<string>
#include<cstring>
using namespace std;
string words[21];
int used[21];
int n,ans;
char start;
int getOverlap(string a,string b){
    int maxOver=min(a.length()-1,b.length()-1);
    for(int i=maxOver;i>=1;i--){
        if(a.substr(a.length()-i)==b.substr(0,i))return i;
    }
    return 0;
}
void dfs(string current,int length){
    if(length>ans)ans=length;
    for(int i=0;i<n;i++){
        if(used[i]>=2)continue;
        int overlap=getOverlap(current,words[i]);
        if(overlap>0){
            used[i]++;
            dfs(words[i],length+words[i].length()-overlap);
            used[i]--;
        }
    }
}
int main(){
    cin>>n;
    for(int i=0;i<n;i++)cin>>words[i];
    cin>>start;
    ans=0;
    for(int i=0;i<n;i++){
        if(words[i][0]==start){
            used[i]=1;
            dfs(words[i],words[i].length());
            used[i]=0;
        }
    }
    cout<<ans<<endl;
    return 0;
}