剑指 Offer II 062. 实现前缀树

剑指 Offer II 062. 实现前缀树

代码如下

思路：

• insert 将字符串解析为对象嵌套，例如"abc"解析为this.obj={a:{b:{c:{isEnd:true}}}}
• 再次插入"abcd时",进一步解析为this.obj = {a:{b:{c:{isEnd:true,d:{isEnd:true}}}}}

var Trie = function () {
    this.obj = {};
};
Trie.prototype.insert = function (word) {
    var node = this.obj;
    for (var s of word) {
        if (!node[s]) {
            node[s] = {};
        }
        node = node[s];
    }
    node.isEnd = true;
};
Trie.prototype.searchPrefix = function (prefix) {
    var node = this.obj;
    for (var s of prefix) {
        if (!node[s]) {
            return false;
        }
        node = node[s];
    }
    return node;
}
Trie.prototype.search = function (word) {
    var node = this.searchPrefix(word);
    return node && node.isEnd !== undefined;
};
Trie.prototype.startsWith = function (prefix) {
    return this.searchPrefix(prefix);
};

var trie = new Trie()
trie.insert("abc")
trie.insert("abcd")
console.log(trie.search("abcd"));