Most Common Word

Most Common Word

Given a string paragraph and a string array of the banned words banned, return the most frequent word that is not banned. It is guaranteed there is at least one word that is not banned, and that the answer is unique.

The words in paragraph are case-insensitive and the answer should be returned in lowercase.

LeetCode Problem - 819

class Solution {
    public String mostCommonWord(String paragraph, String[] banned) {
        // Replace all non-letter characters with spaces and trim the result to clean up the paragraph
        String filteredParagraph = paragraph.replaceAll("[^a-zA-Z]", " ").replaceAll("\\s+", " ").trim();

        // Create a map to count the occurrences of each word
        Map<String, Integer> mp = new HashMap<>();
        // Split the cleaned paragraph into words
        String[] paragraphArray = filteredParagraph.split(" ");
        // Convert the banned array to a string for easier checking
        String bannedString = Arrays.toString(banned);

        // Iterate over each word in the paragraph
        for(int i = 0; i < paragraphArray.length; i++) {
            // Convert the word to lowercase
            String key = paragraphArray[i].toLowerCase();
            // If the word is not in the banned list, update its count in the map
            if(!bannedString.contains(key)) {
                mp.put(key, mp.getOrDefault(key, 0) + 1);

        // Initialize variables to track the most common word and its count
        String answer = "";
        int count = 0;
        // Iterate over the keys in the map
        for(String str : mp.keySet()) {
            // Get the count of the current word
            int temp = mp.get(str);
            // Update the most common word and its count if the current word's count is higher
            if(temp > count) {
                count = temp;
                answer = str;
        // Return the most common word
        return answer;

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