C++ :

#include<iostream>
#include<cstdio>
#include<algorithm>

using namespace  std;
string a[1000];
int n;
int ans=-1,b[10000]={0};
int  jian(string a,string b)//b为原先的单词 
{
	/*if(a==b)
	return 0;*/
	//else
	{
		int p=-1;
		for(int i=b.size()-1;i>=0;--i)
		{
			if(b[i]==a[0])
			{
				p=i;
				break;
			}
		}
		if(p==-1)
		return 0;
		else
		{
			int i=0;
			while(p<=b.size()&&a[i]==b[p])
			{
				p++;
				i++;
			}
			if(p==b.size())
			return i;
			else
			return 0;
		}
	}
}//试验了几次 应该没问题了 但重复中有重复的没有考虑 如abacd gjhgjaba 

int dan(int l,string x,int p)//p为flag x为上次的末尾 l为现在的长度 
{
	if(p==0)
	{
		if(l>ans)
		ans=l;
	}
	else
	{
		int k=0;
		for(int i=2;i<=n+1;++i)
		{
			if(jian(a[i],x)>0&&b[i]<=1)
			{
				k=i;
				b[i]++;
				dan(l+a[i].size()-jian(a[i],x),a[i],k);
				b[i]--;
			}
		}
		if(k==0)
		dan(l,x,0);
	}
}
int main()
{
	//freopen("dcjl.in","r",stdin);
	//freopen("dcjl.out","w",stdout);
	cin>>n;
	for(int i=2;i<=n+1;++i)
	cin>>a[i];
	cin>>a[1];
	dan(1,a[1],1);
	cout<<ans;
}

Pascal :

Program long;
Var
   x:array[1..20]of string;
   f:array[1..20,1..20]of integer;
   start:char;
   n,i,j,k,s1,s2,min,ans:integer;
   g:array[1..20]of integer;
procedure dfs(i,p:integer);
   var j:integer;
   begin
   for j:=1 to n do
      if (g[j]<2)and(f[i,j]<>0)then
         begin
         inc(g[j]);
         dfs(j,p+f[i,j]);
         dec(g[j]);
         end;
   if p>ans then ans:=p;
   end;
Begin
readln(n);
for i:=1 to n do readln(x[i]);
for i:=1 to n do
   for j:=1 to n do
      begin
      s1:=length(x[i]);s2:=length(x[j]);
      if s1<s2 then min:=s1-1 else min:=s2-1;
      for k:=1 to min+1 do
         if (copy(x[i],s1-k+1,k)=copy(x[j],1,k)) then break;
      if k<=min then f[i,j]:=s2-k;
      end;
readln(start);
for i:=1 to n do
   if start=x[i][1] then
      begin
      fillchar(g,sizeof(g),0);
      g[i]:=1;
      dfs(i,length(x[i]));
      end;
writeln(ans);
End.