java刷题--208Trie前缀树

Posted 2021-08-28 Anrys

java刷题--208Trie前缀树

• 题目
• 代码
• 结果

题目

腾讯二面–所以说知识点一定要全

代码

class Trie {
    private Trie[] children;
    private boolean isEnd;
    public Trie() {
        children = new Trie[26];
        isEnd = false;
    }
    public void insert(String word) {
        Trie node = this;
        for (int i = 0; i < word.length(); i++) {
            char ch = word.charAt(i);
            int index = ch - 'a';
            if (node.children[index] == null) {
                node.children[index] = new Trie();
            }node = node.children[index];
        }node.isEnd = true;
    } 
    public boolean search(String word) {
        Trie node = searchPrefix(word);
        return node != null && node.isEnd;
    }
    public boolean startsWith(String prefix) {return searchPrefix(prefix) != null;}
    private Trie searchPrefix(String prefix) {
        Trie node = this;
        for (int i = 0; i < prefix.length(); i++) {
            char ch = prefix.charAt(i);
            int index = ch - 'a';
            if (node.children[index] == null) return null;
            node = node.children[index];
        }return node;
    }
}

结果