Design Add and Search Words Data Structure

 Design a data structure that supports adding new words and finding if a string matches any previously added string.


Implement the WordDictionary class:


WordDictionary() Initializes the object.

void addWord(word) Adds word to the data structure, it can be matched later.

bool search(word) Returns true if there is any string in the data structure that matches word or false otherwise. word may contain dots '.' where dots can be matched with any letter.

 


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

 


Constraints:


1 <= word.length <= 25

word in addWord consists of lowercase English letters.

word in search consist of '.' or lowercase English letters.

There will be at most 2 dots in word for search queries.

At most 104 calls will be made to addWord and search.


class WordDictionary {

    // Root of the trie
    private TrieNode root;

    // TrieNode class
    private class TrieNode {
        TrieNode[] children = new TrieNode[26];
        boolean isEndOfWord = false;
    }

    // Constructor
    public WordDictionary() {
        root = new TrieNode();
    }

    // Add word into the trie
    public void addWord(String word) {
        TrieNode curr = root;

        for (char ch : word.toCharArray()) {
            int index = ch - 'a';
            if (curr.children[index] == null) {
                curr.children[index] = new TrieNode();
            }
            curr = curr.children[index];
        }

        curr.isEndOfWord = true;
    }

    // Search word (with '.' support)
    public boolean search(String word) {
        return searchHelper(word, root);
    }

   
    private boolean searchHelper(String word, TrieNode root) {
        TrieNode curr = root;

        for (int i = 0; i < word.length(); i++) {
            char ch = word.charAt(i);

            if (ch == '.') {
                for (TrieNode child : curr.children) {
                    if (child != null && searchHelper(word.substring(i + 1), child)) {
                        return true;
                    }
                }
                return false;
            } else {
                int index = ch - 'a';
                if (curr.children[index] == null) {
                    return false;
                }
                curr = curr.children[index];
            }
        }

        return curr.isEndOfWord;
    }
}

Comments

Post a Comment

Popular posts from this blog

Two Sum II - Input Array Is Sorted

 Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order , find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length. Return the indices of the two numbers, index1 and index2, added by one as an integer array [index1, index2] of length 2. The tests are generated such that there is exactly one solution. You may not use the same element twice. Your solution must use only constant extra space .   Example 1: Input: numbers = [2,7,11,15], target = 9 Output: [1,2] Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2]. Example 2: Input: numbers = [2,3,4], target = 6 Output: [1,3] Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3]. Example 3: Input: numbers = [-1,0], target = -1 Output: [1,2] Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1,...
Read more

Comparable Vs. Comparator in Java

  In Java , Comparable and Comparator both are interfaces used to sort objects. Comparable It defines  natural ordering  within a class. It is implemented  inside  the class being sorted. It uses the compareTo() method. It allows sorting  by one one . Comparable provides a  single sorting sequence . In other words, we can sort the collection on the basis of a single element such as id, name, and price. Comparable  affects the original class , i.e., the actual class is modified. Comparable is present in  java.lang  package. We can sort the list elements of Comparable type by  Collections.sort(List)  method. Only one compareTo() method can be implemented, restricting flexibility. Comparator It defines  custom sorting logic It is implemented  in a separate class  or using lambda expressions . It uses the compare() method. It allows sorting  by multiple criteria . The Comparator provides  multiple sorting...
Read more

Increasing Triplet Subsequence

 Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return false.   Example 1: Input: nums = [1,2,3,4,5] Output: true Explanation: Any triplet where i < j < k is valid. Example 2: Input: nums = [5,4,3,2,1] Output: false Explanation: No triplet exists. Example 3: Input: nums = [2,1,5,0,4,6] Output: true Explanation: The triplet (3, 4, 5) is valid because nums[3] == 0 < nums[4] == 4 < nums[5] == 6. Brute Force : Failed for some testcase class Solution {     public boolean increasingTriplet ( int [] nums ) {         int n = nums . length ;         int i = 0 ;         int j =i+ 1 ;         int k =j+ 1 ;         while (i <n && j<n && k<n)         {         if (nums...
Read more