package LeetCode_208
/**
* 208. Implement Trie (Prefix Tree)
* https://leetcode.com/problems/implement-trie-prefix-tree/description/
* */
class Trie() {
private var root: TireNode? = null
class TireNode {
var children = arrayOfNulls<TireNode>(26)
var isWord = false
}
/** Initialize your data structure here. */
init {
root = TireNode()
println(root?.children?.size)
}
/** Inserts a word into the trie. */
fun insert(word: String) {
var p = root
for (c in word) {
val index = c.toInt() - 'a'.toInt()
if (p?.children?.get(index) == null) {
p?.children?.set(index, TireNode())
}
p = p?.children?.get(index)
}
p?.isWord = true
}
/** Returns if the word is in the trie. */
fun search(word: String): Boolean {
val node = find(word)
return node != null && node?.isWord
}
/** Returns if there is any word in the trie that starts with the given prefix. */
fun startsWith(prefix: String): Boolean {
val node = find(prefix)
return node != null
}
private fun find(prefix: String): TireNode? {
var p = root
for (c in prefix) {
val index = c.toInt() - 'a'.toInt()
if (p?.children?.get(index) == null) {
return null
}
p = p?.children?.get(index)
}
return p
}
}
/**
* Your Trie object will be instantiated and called as such:
* var obj = Trie()
* obj.insert(word)
* var param_2 = obj.search(word)
* var param_3 = obj.startsWith(prefix)
*/
