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<p>我有一个国家的名单，我想有一个最长的国家路径，每个国家选择必须以相同的字母结束前一个元素</p>
<pre><code>nations = ['albania','andorra','austria','belarus','belgium','bosnia and herzegovina',
'bulgaria','croatia','czech republic','denmark','estonia',
'finland','france','germany','greece','hungary',
'iceland','ireland','italy','latvia','liechtenstein','lithuania','luxembourg',
'macedonia','malta','moldova','monaco','montenegro','netherlands',
'norway','poland','portugal','romania','russia',
'san marino','serbia','slovakia','slovenia','spain','sweden', 'switzerland',
'ukraine','united kingdom','vatican city']
chain('spain')
>>>['spain', 'netherlands', 'slovenia', 'andorra', 'austria', 'albania']
</code></pre>
<p>我试过这样做，但没用</p>
^{pr2}$
<p>有什么建议吗？在</p>
