算法：字典树（Trie)-理论与实战

​class Trie {
    class TrieNode {
        char value;
        TrieNode[] childer;
        Boolean isEng = false;   //下面是否有节点

        public TrieNode(char c) {
            this.value = c;
            childer = new TrieNode[26];//仅限26个小写之母
        }
    }

    TrieNode root;

    /**
     * Initialize your data structure here.
     */
    public Trie() {
        root = new TrieNode('/');
    }

    /**
     * Inserts a word into the trie.
     */
    public void insert(String word) {      //插入
        TrieNode p = root;
/*        for (int i = 0; i < word.length(); i++) {
//            if (p.childer[word.length() - 'a'] == word.charAt(i))
            if (p.childer[word.charAt(i) - 'a'] == null) {
                p.childer[word.charAt(i) - 'a'] = new TrieNode(word.charAt(i));
            }
            p = p.childer[word.charAt(i) - 'a'];
        }*/
        for (char c : word.toCharArray()) {         //简写
            if (p.childer[c - 'a'] == null) p.childer[c - 'a'] = new TrieNode(c);
            p = p.childer[c - 'a'];
        }
        p.isEng = true;
    }

    /**
     * Returns if the word is in the trie.
     */
    public boolean search(String word) {     //搜索全部，即最后节点为Nil
        TrieNode p = root;
        for (char c : word.toCharArray()) {
            if (p.childer[c - 'a'] == null) return false;
            p = p.childer[c - 'a'];
        }
        /*for (int i = 0; i < word.length(); i++) {
            if (p.childer[word.charAt(i) - 'a'] == null) return false;
            p = p.childer[word.charAt(i) - 'a'];
        }*/
        return p.isEng;
    }

    /**
     * Returns if there is any word in the trie that starts with the given prefix.
     */
    public boolean startsWith(String prefix) {        //只要匹配即可以
        TrieNode p = root;
        for (char c : prefix.toCharArray()) {
            if (p.childer[c - 'a'] == null) return false;
            p = p.childer[c - 'a'];
        }
        return true;
    }
}