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// @Title: 实现 Trie (前缀树) (Implement Trie (Prefix Tree))
// @Author: 15816537946@163.com
// @Date: 2020-06-25 07:15:36
// @Runtime: 60 ms
// @Memory: 18.1 MB
/*
 * @lc app=leetcode.cn id=208 lang=golang
 *
 * [208] 实现 Trie (前缀树)
 *
 * https://leetcode-cn.com/problems/implement-trie-prefix-tree/description/
 *
 * algorithms
 * Medium (60.91%)
 * Likes:    113
 * Dislikes: 0
 * Total Accepted:    12K
 * Total Submissions: 19.7K
 * Testcase Example:  '["Trie","insert","search","search","startsWith","insert","search"]\n[[],["apple"],["apple"],["app"],["app"],["app"],["app"]]'
 *
 * 实现一个 Trie (前缀树),包含 insert, search, 和 startsWith 这三个操作。
 *
 * 示例:
 *
 * Trie trie = new Trie();
 *
 * trie.insert("apple");
 * trie.search("apple");   // 返回 true
 * trie.search("app");     // 返回 false
 * trie.startsWith("app"); // 返回 true
 * trie.insert("app");
 * trie.search("app");     // 返回 true
 *
 * 说明:
 *
 *
 * 你可以假设所有的输入都是由小写字母 a-z 构成的。
 * 保证所有输入均为非空字符串。
 *
 *
 */

 /*
type Trie struct {
	val      rune
	children [26]*Trie
	isEnd    bool
}

func Constructor() Trie {
	return Trie{}
}

func (this *Trie) Insert(word string) {
	if word == "" {
		return
	}

	root := this
	var idx int
	for _, v := range word {
		idx = int(v - 'a')
		if root.children[idx] == nil {
			root.children[idx] = &Trie{val: v}
		}

		root = root.children[idx]
	}
	root.isEnd = true

}

func (this *Trie) Search(word string) bool {
	if word == "" {
		return false
	}

	root := this
	var idx int
	for _, v := range word {
		idx = int(v - 'a')
		if root.children[idx] == nil {
			return false
		}
		root = root.children[idx]
	}

	return root.isEnd
}

func (this *Trie) StartsWith(prefix string) bool {
	if prefix == "" {
		return false
	}

	root := this
	var idx int
	for _, v := range prefix {
		idx = int(v - 'a')
		if root.children[idx] == nil {
			return false
		}

		root = root.children[idx]
	}
	return true

}
*/

type Trie struct {
	isEnd    bool
	// val      rune
	children [26]*Trie
}

func Constructor() Trie {
	return Trie{}
}

func (this *Trie) Insert(word string) {
	if word == "" {
		return
	}

	cursor := this
	var idx int
	for _, w := range word {
		idx = int(w - 'a')
		if cursor.children[idx] == nil {
			// cursor.children[idx] = &Trie{val: w}
			cursor.children[idx] = &Trie{}
		}
		cursor = cursor.children[idx]
	}
	cursor.isEnd = true
}

func (this *Trie) Search(word string) bool {
	if word == "" {
		return false
	}

	var idx int
	cursor := this
	for _, w := range word {
		idx = int(w - 'a')
		if cursor.children[idx] == nil {
			return false
		}

		cursor = cursor.children[idx]
	}

	return cursor.isEnd
}

func (this *Trie) StartsWith(word string) bool {
	if word == ""{
		return false
	}

	cursor := this
	var idx int
	for _, w := range word {
		idx = int(w - 'a')
		if cursor.children[idx] == nil {
			return false
		}

		cursor = cursor.children[idx]
	}

	return true
}

/**
 * Your Trie object will be instantiated and called as such:
 * obj := Constructor();
 * obj.Insert(word);
 * param_2 := obj.Search(word);
 * param_3 := obj.StartsWith(prefix);
 */