51分求助（QAQ）

#include<bits/stdc++.h>
using namespace std;

string s[25];
int n;
char start;
long long maxx = 0;
int visit[25];

int get_less(string a, string b) {
    int max_possible = min(a.size(), b.size());
    for (int k = max_possible; k > 0; k--) {
        if (a.substr(a.size() - k) == b.substr(0, k)) {
            return k;
        }
    }
    return 0;
}

void search(int id, int cd, string front) {
    if (cd > maxx) {
        maxx = cd;
    }
    for (int i = 0; i < n; i++) {
        if (visit[i] < 2) {
            int less = get_less(front, s[i]);
            if (less > 0 && less < s[i].size() && less < front.size()) {
                visit[i]++;
                search(i, cd + s[i].size() - less, s[i]);
                visit[i]--;
            }
        }
    }
}

int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    cin >> start;
    for (int i = 0; i < n; i++) {
        if (s[i][0] == start) {
            visit[i]++;
            search(i, s[i].size(), s[i]);
            visit[i]--;
        }
    }
    cout << maxx;
    return 0;
}