leetcode-java/src/ImplementTriePrefixTree208.java at master · fluency03/leetcode-java · GitHub

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/**
 * Implement a trie with insert, search, and startsWith methods.
 *
 * Example:
 *
 * Trie trie = new Trie();
 *
 * trie.insert("apple");
 * trie.search("apple"); // returns true
 * trie.search("app"); // returns false
 * trie.startsWith("app"); // returns true
 * trie.insert("app");
 * trie.search("app"); // returns true
 *
 * Note:
 * You may assume that all inputs are consist of lowercase letters a-z.
 * All inputs are guaranteed to be non-empty strings.
 */


publicclassImplementTriePrefixTree208 {

classTrie {

privateTrie[] children = newTrie[26];
privatebooleanisWord = false;

/** Initialize your data structure here. */
publicTrie() {

 }

/** Inserts a word into the trie. */
publicvoidinsert(Stringword) {
insert(word.toCharArray(), 0);
 }

privatevoidinsert(char[] chars, inti) {
if (i == chars.length) {
this.isWord = true;
return;
 }
if (this.children[chars[i]-'a'] == null) {
this.children[chars[i]-'a'] = newTrie();
 }
this.children[chars[i]-'a'].insert(chars, i+1);
 }

/** Returns if the word is in the trie. */
publicbooleansearch(Stringword) {
returnsearch(word.toCharArray(), 0);
 }

privatebooleansearch(char[] chars, inti) {
if (i == chars.length) returnthis.isWord;
if (this.children[chars[i]-'a'] == null) returnfalse;
returnthis.children[chars[i]-'a'].search(chars, i+1);
 }

/** Returns if there is any word in the trie that starts with the given prefix. */
publicbooleanstartsWith(Stringprefix) {
returnstartsWith(prefix.toCharArray(), 0);
 }

privatebooleanstartsWith(char[] chars, inti) {
if (i == chars.length) returntrue;
if (this.children[chars[i]-'a'] == null) returnfalse;
returnthis.children[chars[i]-'a'].startsWith(chars, i+1);
 }

 }


/**
 * https://leetcode.com/problems/implement-trie-prefix-tree/solution/
 */
classTrie2 {
privateTrieNoderoot;

/** Initialize your data structure here. */
publicTrie() {
root = newTrieNode();
 }

/** Inserts a word into the trie. */
publicvoidinsert(Stringword) {
TrieNodenode = root;
for (inti = 0; i < word.length(); i++) {
charc = word.charAt(i);
if (!node.containsKey(c)) {
node.put(c, newTrieNode());
 }
node = node.get(c);
 }
node.setLeaf();
 }

/** Returns if the word is in the trie. */
publicbooleansearch(Stringword) {
TrieNodenode = root;
for (inti = 0; i < word.length(); i++) {
charc = word.charAt(i);
if (!node.containsKey(c)) {
returnfalse;
 }
node = node.get(c);
 }
returnnode.isLeaf();
 }

/** Returns if there is any word in the trie that starts with the given prefix. */
publicbooleanstartsWith(Stringprefix) {
TrieNodenode = root;
for (inti = 0; i < prefix.length(); i++) {
charc = prefix.charAt(i);
if (!node.containsKey(c)) {
returnfalse;
 }
node = node.get(c);
 }
returntrue;
 }
 }

classTrieNode {
// R links to node children
privateTrieNode[] links;

privatefinalintR = 26;

privatebooleanisLeaf;

publicTrieNode() {
links = newTrieNode[R];
 }

publicbooleancontainsKey(charc) {
returnlinks[c -'a'] != null;
 }
publicTrieNodeget(charc) {
returnlinks[c -'a'];
 }
publicvoidput(charc, TrieNodenode) {
links[c -'a'] = node;
 }
publicvoidsetLeaf() {
isLeaf = true;
 }
publicbooleanisLeaf() {
returnisLeaf;
 }
 }


/**
 * Your Trie object will be instantiated and called as such:
 * Trie obj = new Trie();
 * obj.insert(word);
 * boolean param_2 = obj.search(word);
 * boolean param_3 = obj.startsWith(prefix);
 */


}