leetcode 前缀树trie整理

class Trie {

    Trie[] children;
    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 c = word.charAt(i);
            int index = c - '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 = this;
        for(int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);
            int index = c - 'a';
            if (node.children[index] != null){
                node = node.children[index];
            } else return false;
        }
        if (node.isEnd) return true;
        return false;
    }
    
    public boolean startsWith(String prefix) {
        Trie node = this;
        for(int i = 0; i < prefix.length(); i++) {
            char c = prefix.charAt(i);
            int index = c - 'a';
            if (node.children[index] != null){
                node = node.children[index];
            } else return false;
        }
        return true;
    }
}
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