Fix link to additional files after contest ends

views/problem.ejs

@@ -91,7 +91,7 @@ div[class*=ace_br] {
           <a class="small ui orange button" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'statistics', problem.type === 'submit-answer' ? 'min' : 'fastest']) %>">统计</a>
           <a class="small ui yellow button" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata']) %>">测试数据</a>
         <% } %>
-        <% if (problem.additional_file) { %><a class="small ui teal button" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'download', 'additional_file'], contest ? { contest_id: contest.id } : undefined) %>">附加文件</a><% } %>
+        <% if (problem.additional_file) { %><a class="small ui teal button" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'download', 'additional_file'], (contest && !contest.ended) ? { contest_id: contest.id } : undefined) %>">附加文件</a><% } %>
       </div>
       <% if (!contest) { %>
         <div class="ui buttons right floated">