#include <bits/stdc++.h>
using namespace std;
const int N = 605;
char s[51];
int ch[N][26], id, ed[N], pre[N], v[N][1 << 12 | 1], c[N];
struct node { int c, pre; } a[N * (1 << 12 | 1)];

void ins(char *s, int x) {
    int p = 0;
    for (int i = 0; s[i]; i++) {
        int j = s[i] - 'A';
        if (ch[p][j] == 0) ch[p][j] = ++id;
        p = ch[p][j];
    }
    ed[p] |= 1 << (x - 1);
}

void build() {
    queue<int> Q;
    for (int i = 0; i < 26; i++) if (ch[0][i]) Q.push(ch[0][i]);
    while (!Q.empty()) {
        int x = Q.front(); Q.pop();
        ed[x] |= ed[pre[x]];
        for (int i = 0; i < 26; i++) {
            int &y = ch[x][i];
            if (y == 0) y = ch[pre[x]][i];
            else pre[y] = ch[pre[x]][i], Q.push(y);
        }
    }
}

int main() {
    int n, m; scanf("%d", &n);
    id = 0; memset(ch, 0, sizeof(ch)); memset(ed, 0, sizeof(ed));
    for (int i = 1; i <= n; i++) {
        scanf("%s", s);
        ins(s, i);
    }
    memset(pre, 0, sizeof(pre)); build();
    queue<pair<int, int>> Q;
    memset(v, 0, sizeof(v));
    Q.push({0, 0}); v[0][0] = 1;
    int head = 0, tail = 0, pp;
    while (Q.size()) {
        int x = Q.front().first, st = Q.front().second; Q.pop();
        if (st == ((1 << n) - 1)) { pp = head; break; }
        for (int i = 0; i < 26; i++) {
            int y = ch[x][i];
            if (!v[y][st | ed[y]]) {
                v[y][st | ed[y]] = 1;
                Q.push({y, st | ed[y]});
                tail++; a[tail] = node{i, head};
            }
        }
        head++;
    }
    int cn = 0;
    while (pp) c[++cn] = a[pp].c, pp = a[pp].pre;
    for (int i = cn; i >= 1; i--) printf("%c", c[i] + 'A');
    return 0;
}

看完正解请自行前往此处吃史。

挑战评测机的卡常代码：

#include<bits/stdc++.h>
using namespace std;
const int N=610,M=5010;
int ch[N][26],pre[N],ed[N],len,x;
void ins(string s)
{
	int n=s.size(),p=0;
	for(int i=0;i<n;i++)
	{
		int j=s[i]-'A';
		if(!ch[p][j])ch[p][j]=++len;
		p=ch[p][j];
	}
	if(ed[p])x--;
	else ed[p]=x;
}
void build()
{
	deque<int>q;
	for(int i=0;i<26;i++)if(ch[0][i])q.push_back(ch[0][i]);
	while(!q.empty())
	{
		int x=q.front();q.pop_front();
		for(int j=0;j<26;j++)
		{
			int y=ch[x][j];
			if(!y)ch[x][j]=ch[pre[x]][j];
			else pre[y]=ch[pre[x]][j],q.push_back(y);
		}
	}
}
int dp[N][M],v[N];
int dfs(int x)
{
	if(v[x]!=-1)return v[x];
	v[x]=dfs(pre[x]);
	if(ed[x])v[x]|=(1<<(ed[x]-1));
	return v[x];
}
struct node{int f,id;string s;};
signed main()
{
	int n;cin>>n;
	for(int i=1;i<=n;i++)
	{
		string s;cin>>s;
		x++;ins(s);
	}
	build();
	memset(v,-1,sizeof(v));v[0]=0;for(int i=1;i<=len;i++)dfs(i);
	deque<node>q;q.push_back({0,0,""});dp[0][0]=1;
	while(!q.empty())
	{
		node no=q.front();q.pop_front();
		if(no.f==(1<<x)-1)
		{
			cout<<no.s;
			return 0;
		}
		for(int i=0;i<26;i++)
		{
			int j=ch[no.id][i],f=no.f|v[j];
			if(!dp[j][f])dp[j][f]=1,q.push_back({f,j,no.s+(char)('A'+i)});
		}
	}
	return 0;
}