[英]Efficient way of finding all strings of an Arraylist, which contains a substring
[英]Is there an efficient way to detect if a string contains a substring which is in a large set of characteristic strings?
例如,給定一個字符串aaaaaaaaaXyz
,我想知道它是否包含一個 substring ,它位於特征字符串集中{'xy','xyz','zzz','cccc','dddd',....}
,它可能有 100 萬個成員。 有沒有有效的方法?
鑒於您的搜索集可能非常大,我建議只迭代該集並檢查潛在的 substring 匹配:
public boolean containsSubstring(String input, Set<String> subs) {
boolean match = false;
for (String sub : subs) {
if (input.contains(sub)) {
match = true;
break;
}
}
return match;
}
首先,你准備dictionary
。 像這樣
Set<String> stringSet = Set.of("xy", "xyz", "zzz", "zzy", "cccc", "dddd");
Map<Character, List<String>> dictionary = new HashMap<>();
for (String word : stringSet)
dictionary.computeIfAbsent(word.charAt(0), k -> new ArrayList<>()).add(word);
System.out.println(dictionary);
output:
{c=[cccc], d=[dddd], x=[xyz, xy], z=[zzy, zzz]}
您可以使用此方法找出答案。
static boolean contains(String input, Map<Character, List<String>> dictionary) {
for (int i = 0, max = input.length(); i < max; ++i) {
char first = input.charAt(i);
if (dictionary.containsKey(first))
for (String word : dictionary.get(first))
if (input.startsWith(word, i))
return true;
}
return false;
}
在Clashsoft的提示下,我找到了 Aho-Corasick 算法的 java 實現,這是我想要的,感謝 Clashsoft
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