Solution.go

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

func newTrie() Trie {
	return Trie{}
}

func (this *Trie) Insert(word string) {
	node := this
	for i := len(word) - 1; i >= 0; i-- {
		idx := word[i] - 'a'
		if node.children[idx] == nil {
			node.children[idx] = &Trie{}
		}
		node = node.children[idx]
	}
	node.isEnd = true
}

func (this *Trie) Search(word []byte) bool {
	node := this
	for i := len(word) - 1; i >= 0; i-- {
		idx := word[i] - 'a'
		if node.children[idx] == nil {
			return false
		}
		node = node.children[idx]
		if node.isEnd {
			return true
		}
	}
	return false
}

type StreamChecker struct {
	trie Trie
	s    []byte
}

func Constructor(words []string) StreamChecker {
	trie := newTrie()
	for _, w := range words {
		trie.Insert(w)
	}
	return StreamChecker{trie, []byte{}}
}

func (this *StreamChecker) Query(letter byte) bool {
	this.s = append(this.s, letter)
	return this.trie.Search(this.s)
}

/**
 * Your StreamChecker object will be instantiated and called as such:
 * obj := Constructor(words);
 * param_1 := obj.Query(letter);
 */