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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0701_0800.s0792_number_of_matching_subsequences;

// #Medium #String #Hash_Table #Sorting #Trie #2022_03_26_Time_92_ms_(84.26%)_Space_118_MB_(25.03%)

import java.util.ArrayList;
import java.util.List;

/**
 * 792 - Number of Matching Subsequences\.
 *
 * Medium
 *
 * Given a string `s` and an array of strings `words`, return _the number of_ `words[i]` _that is a subsequence of_ `s`.
 *
 * A **subsequence** of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.
 *
 * *   For example, `"ace"` is a subsequence of `"abcde"`.
 *
 * **Example 1:**
 *
 * **Input:** s = "abcde", words = ["a","bb","acd","ace"]
 *
 * **Output:** 3
 *
 * **Explanation:** There are three strings in words that are a subsequence of s: "a", "acd", "ace". 
 *
 * **Example 2:**
 *
 * **Input:** s = "dsahjpjauf", words = ["ahjpjau","ja","ahbwzgqnuk","tnmlanowax"]
 *
 * **Output:** 2 
 *
 * **Constraints:**
 *
 * *   1 <= s.length <= 5 * 10⁴
 * *   `1 <= words.length <= 5000`
 * *   `1 <= words[i].length <= 50`
 * *   `s` and `words[i]` consist of only lowercase English letters.
**/
@SuppressWarnings("unchecked")
public class Solution {
    public int numMatchingSubseq(String s, String[] words) {
        List[] buckets = new ArrayList[26];
        for (int i = 0; i < buckets.length; i++) {
            buckets[i] = new ArrayList<>();
        }
        for (String word : words) {
            char start = word.charAt(0);
            buckets[start - 'a'].add(new Node(word, 0));
        }
        int result = 0;
        for (char c : s.toCharArray()) {
            List currBucket = buckets[c - 'a'];
            buckets[c - 'a'] = new ArrayList<>();
            for (Node node : currBucket) {
                node.index++;
                if (node.index == node.word.length()) {
                    result++;
                } else {
                    char start = node.word.charAt(node.index);
                    buckets[start - 'a'].add(node);
                }
            }
        }
        return result;
    }

    private static class Node {
        String word;
        int index;

        public Node(String word, int index) {
            this.word = word;
            this.index = index;
        }
    }
}