Algorithm
Problem Name: 819. Most Common Word
Problem Link: https://leetcode.com/problems/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.
Example 1:
Input: paragraph = "Bob hit a ball, the hit BALL flew far after it was hit.", banned = ["hit"] Output: "ball" Explanation: "hit" occurs 3 times, but it is a banned word. "ball" occurs twice (and no other word does), so it is the most frequent non-banned word in the paragraph. Note that words in the paragraph are not case sensitive, that punctuation is ignored (even if adjacent to words, such as "ball,"), and that "hit" isn't the answer even though it occurs more because it is banned.
Example 2:
Input: paragraph = "a.", banned = [] Output: "a"
Constraints:
1 <= paragraph.length <= 1000- paragraph consists of English letters, space
' ', or one of the symbols:"!?',;.". 0 <= banned.length <= 1001 <= banned[i].length <= 10banned[i]consists of only lowercase English letters.
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
class Solution {
public:
string mostCommonWord(string paragraph, vector<string>& banned) {
unordered_mapm;
for(int i = 0; i < paragraph.size();){
string s = "";
while(i < paragraph.size() && isalpha(paragraph[i])) s.push_back(tolower(paragraph[i++]));
while(i < paragraph.size() && !isalpha(paragraph[i])) i++;
m[s]++;
}
for(auto x: banned) m[x] = 0;
string res = "";
int count = 0;
for(auto x: m)
if(x.second > count) res = x.first, count = x.second;
return res;
}
};
Input
paragraph = "Bob hit a ball, the hit BALL flew far after it was hit.", banned = ["hit"]
Output
"ball"
#2 Code Example with Java Programming
Code -
Java Programming
class Solution {
public static String mostCommonWord(String paragraph, String[] banned) {
paragraph = paragraph.toLowerCase();
List < String> bannedWords = Arrays.asList(banned);
String[] words = paragraph.trim().split("\\s+");
Map < String, Integer> map = new LinkedHashMap<>();
int maxValue = Integer.MIN_VALUE;
for (String word : words) {
if (!Character.isAlphabetic(word.charAt(word.length()-1))) {
word = word.substring(0, word.length()-1);
}
if (!(word.equals(" ") || word.equals("")) && bannedWords.indexOf(word) == -1) {
map.put(word, map.getOrDefault(word, 0) + 1);
maxValue = Math.max(maxValue, map.get(word));
}
}
for (String word : map.keySet()) {
if (map.get(word) == maxValue) {
return word;
}
}
return "";
}
}
Input
paragraph = "Bob hit a ball, the hit BALL flew far after it was hit.", banned = ["hit"]
Output
"ball"
#3 Code Example with Javascript Programming
Code -
Javascript Programming
const mostCommonWord = function(paragraph, banned) {
const str = paragraph.toLowerCase()
const arr = str.replace(/\W+/g, ' ').trim().split(' ')
const hash = {}
for(let el of arr) {
if(banned.indexOf(el) !== -1) {
} else {
if(hash.hasOwnProperty(el)) {
hash[el] += 1
} else {
hash[el] = 1
}
}
}
const res = Object.entries(hash).sort((a, b) => b[1] - a[1])
return res[0][0]
};
Input
paragraph = "a.", banned = []
Output
"a"
#4 Code Example with Python Programming
Code -
Python Programming
class Solution:
def mostCommonWord(self, paragraph, banned):
"""
:type paragraph: str
:type banned: List[str]
:rtype: str
"""
paragraph = re.findall(r"\u005Cw+", paragraph)
dic = {}
mx = [0, 0]
for char in paragraph:
char = char.lower()
if char not in banned:
if char not in dic: dic[char] = 1
else: dic[char] += 1
mx[0] = max(mx[0], dic[char])
if mx[0] == dic[char]: mx[1] = char
return mx[1]
Input
paragraph = "a.", banned = []
Output
"a"
#5 Code Example with C# Programming
Code -
C# Programming
using System;
using System.Collections.Generic;
namespace LeetCode
{
public class _0819_MostCommonWord
{
public string MostCommonWord(string paragraph, string[] banned)
{
var split = paragraph.Replace('!', ' ').Replace('?', ' ').Replace('\'', ' ').Replace(',', ' ').Replace(';', ' ').Replace('.', ' ').ToLower().Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
var bannedSet = new HashSet < string>(banned);
var counts = new Dictionary();
foreach (var word in split)
{
if (bannedSet.Contains(word))
continue;
if (counts.ContainsKey(word))
counts[word]++;
else
counts[word] = 1;
}
var max = 0;
var result = string.Empty;
foreach (var pair in counts)
{
if (max < pair.Value)
{
max = pair.Value;
result = pair.Key;
}
}
return result;
}
}
}
Input
paragraph = "Bob hit a ball, the hit BALL flew far after it was hit.", banned = ["hit"]
Output
"ball"