Leet Code 211. Design Add and Search Words Data Structure

https://leetcode.com/problems/design-add-and-search-words-data-structure/

Example:

Input
["WordDictionary","addWord","addWord","addWord","search","search","search","search"]
[[],["bad"],["dad"],["mad"],["pad"],["bad"],[".ad"],["b.."]]
Output
[null,null,null,null,false,true,true,true]

Explanation
WordDictionary wordDictionary = new WordDictionary();
wordDictionary.addWord("bad");
wordDictionary.addWord("dad");
wordDictionary.addWord("mad");
wordDictionary.search("pad"); // return False
wordDictionary.search("bad"); // return True
wordDictionary.search(".ad"); // return True
wordDictionary.search("b.."); // return True

package pep.Day79;

public class LeetCode_211_Design_Add_and_Search_Words_DataStructure {

    static class WordDictionary {

        static class Node {
            Node children[];
            boolean isEnding;

            Node() {
                children = new Node[26];
            }

            public boolean find(String word) {
                if (word.length() == 0)
                    return isEnding;

                char ch = word.charAt(0);
                if (ch == '.') {
                    int i = 0;
                    for (Node child : this.children) {
                        System.out.println(i++);
                        if (child != null && child.find(word.substring(1)) == true)
                            return true;
                    }
                } else {
                    // children me woh character nhi hai
                    if (children[ch - 'a'] == null)
                        return false;
                    else {
                        // children me woh character mil gya
                        return children[ch - 'a'].find(word.substring(1));
                    }
                }

                return false;
            }
        }

        static Node root;

        public WordDictionary() {
            root = new Node();
        }

        public static void addWord(String word) {
            Node current = root;
            for (int i = 0; i < word.length(); i++) {
                if (current.children[word.charAt(i) - 'a'] == null)
                    current.children[word.charAt(i) - 'a'] = new Node();
                current = current.children[word.charAt(i) - 'a'];
            }

            current.isEnding = true;
        }

        public boolean search(String word) {
            return root.find(word);
        }

    }

    public static void main(String[] args) {
        WordDictionary wd = new WordDictionary();
        wd.addWord("car");
        wd.addWord("cat");
        System.out.println(wd.search("c.m"));
    }


}