LeetCode-in-Java

1268. Search Suggestions System

Medium

You are given an array of strings products and a string searchWord.

Design a system that suggests at most three product names from products after each character of searchWord is typed. Suggested products should have common prefix with searchWord. If there are more than three products with a common prefix return the three lexicographically minimums products.

Return a list of lists of the suggested products after each character of searchWord is typed.

Example 1:

Input: products = [“mobile”,”mouse”,”moneypot”,”monitor”,”mousepad”], searchWord = “mouse”

Output:

[ 
    ["mobile","moneypot","monitor"], 
    ["mobile","moneypot","monitor"], 
    ["mouse","mousepad"], 
    ["mouse","mousepad"], 
    ["mouse","mousepad"] 
                            ]

Explanation: products sorted lexicographically = [“mobile”,”moneypot”,”monitor”,”mouse”,”mousepad”] After typing m and mo all products match and we show user [“mobile”,”moneypot”,”monitor”] After typing mou, mous and mouse the system suggests [“mouse”,”mousepad”]

Example 2:

Input: products = [“havana”], searchWord = “havana”

Output: [[“havana”],[“havana”],[“havana”],[“havana”],[“havana”],[“havana”]]

Example 3:

Input: products = [“bags”,”baggage”,”banner”,”box”,”cloths”], searchWord = “bags”

Output: [[“baggage”,”bags”,”banner”],[“baggage”,”bags”,”banner”],[“baggage”,”bags”],[“bags”]]

Constraints:

• 1 <= products.length <= 1000
• 1 <= products[i].length <= 3000
• 1 <= sum(products[i].length) <= 2 * 104
• All the strings of products are unique.
• products[i] consists of lowercase English letters.
• 1 <= searchWord.length <= 1000
• searchWord consists of lowercase English letters.

Solution

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

public class Solution {
    public List<List<String>> suggestedProducts(String[] products, String searchWord) {
        Trie trie = new Trie();
        Arrays.sort(products);
        for (String p : products) {
            trie.insert(p);
        }

        return trie.getResult(searchWord);
    }

    static class Trie {
        Node root;

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

        void insert(String word) {
            Node curr = root;
            for (int i = 0; i < word.length(); i++) {
                char c = word.charAt(i);
                if (!curr.containsKey(c)) {
                    curr.put(c, new Node());
                }
                curr = curr.get(c);
                curr.addToList(word);
            }
        }

        List<List<String>> getResult(String searchWord) {
            Node curr = root;
            List<List<String>> res = new ArrayList<>();
            for (int i = 0; i < searchWord.length(); i++) {
                char c = searchWord.charAt(i);
                List<String> temp = new ArrayList<>();
                if (curr != null) {
                    curr = curr.get(c);
                }

                for (int j = 0; j < 3 && curr != null && j < curr.getList().size(); j++) {
                    temp.add(curr.getList().get(j));
                }
                res.add(new ArrayList<>(temp));
            }
            return res;
        }
    }

    static class Node {
        Node[] links;
        List<String> list;

        public Node() {
            links = new Node[26];
            list = new ArrayList<>();
        }

        boolean containsKey(char c) {
            return links[c - 'a'] != null;
        }

        Node get(char c) {
            return links[c - 'a'];
        }

        void put(char c, Node node) {
            links[c - 'a'] = node;
        }

        void addToList(String s) {
            list.add(s);
        }

        List<String> getList() {
            return list;
        }
    }
}

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