给定一个字符串列表：
ArrayList<String> strList = new ArrayList<String>();
strList.add("Mary had a little lamb named Willy");
strList.add("Mary had a little ham");
strList.add("Old McDonald had a farm named Willy");
strList.add("Willy had a little dog named ham");
strList.add("(abc)");
strList.add("(xyz)");
strList.add("Visit Target Store");
strList.add("Visit Walmart Store");
HashMap<String, Integer> prefixMap这应该产生 a和形式的输出suffixMap：
字首：
Mary had a -> 2
Mary had a little -> 2
( -> 2
Visit -> 2
后缀：
named Willy -> 2
ham -> 2
) -> 2
Store -> …