题目链接

代码

#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
using namespace std;
int n,ans[1005],ansn,a[1005][1005],b[1005][1005];
bool u[1005];
string s[1005];
bool cmp(string s,string st){return s<st;};
void dfs(int x)
{
	for(int i=1;i<=n;i++)if(b[x][i]&&!u[i])
	{
		b[x][i]--;
		u[i]=1;
		dfs(i);
	}
	ans[++ansn]=x;
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)cin>>s[i];
	sort(s+1,s+n+1,cmp);
	for(int i=1;i<=n;i++)for(int j=1;j<=n;j++)if(s[i][0]==s[j][s[j].size()-1])a[j][i]++;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)for(int k=1;k<=n;k++)b[j][k]=a[j][k];
		u[i]=1;
		dfs(i);
		if(ansn>=n)
		{
			for(int i=n;i>1;i--)cout<<s[ans[i]]<<".";
			cout<<s[ans[1]];
			return 0;
		}
		for(int j=1;j<=n;j++)u[j]=0;
		ansn=0;
	}
	cout<<"***";	
	return 0;
}