solve problem Most Common Word

Author: P-ppc

README.md

@@ -133,6 +133,7 @@ All solutions will be accepted!
 |504|[Base 7](https://leetcode-cn.com/problems/base-7/description/)|[java/py/js](./algorithms/Base7)|Easy|
 |830|[Positions Of Large Groups](https://leetcode-cn.com/problems/positions-of-large-groups/description/)|[java/py/js](./algorithms/PositionsOfLargeGroups)|Easy|
 |572|[Subtree Of Another Tree](https://leetcode-cn.com/problems/subtree-of-another-tree/description/)|[java/py/js](./algorithms/Subtree Of Another Tree)|Easy|
+|819|[Most Common Word](https://leetcode-cn.com/problems/most-common-word/description/)|[java/py/js](./algorithms/MostCommonWord)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/MostCommonWord/README.md

@@ -0,0 +1,2 @@
+# Most Common Word
+This problem is easy to solve

algorithms/MostCommonWord/Solution.java

@@ -0,0 +1,34 @@
+class Solution {
+    public String mostCommonWord(String paragraph, String[] banned) {
+        Map<String, Integer> wordsMap = new HashMap<String, Integer>();
+        List<String> words = new ArrayList<String>();
+        String res = null;
+        int maxCount = 0;
+        
+        paragraph = paragraph.toLowerCase();
+        paragraph = paragraph.replaceAll("[!?',;.]", "");
+        
+        for (int i = 0; i < banned.length; i++) {
+            banned[i] = banned[i].toLowerCase();
+        }
+        
+        for (String word : paragraph.split(" ")) {
+            if (wordsMap.get(word) == null) {
+                wordsMap.put(word, 1);
+                words.add(word);
+            } else {
+                wordsMap.put(word, wordsMap.get(word) + 1);
+            }
+        }
+        
+        for (int i = 0; i < words.size(); i++) {
+            String word = words.get(i);
+            if (!Arrays.asList(banned).contains(word) && wordsMap.get(word) > maxCount) {
+                res = word;
+                maxCount = wordsMap.get(word);
+            }
+        }
+        
+        return res;
+    }
+}

algorithms/MostCommonWord/solution.js

@@ -0,0 +1,32 @@
+/**
+ * @param {string} paragraph
+ * @param {string[]} banned
+ * @return {string}
+ */
+var mostCommonWord = function(paragraph, banned) {
+    let wordsMap = {},
+        words = [],
+        res = null,
+        maxCount = 0
+    
+    paragraph = paragraph.toLowerCase()
+    paragraph = paragraph.replace(/[!?',;.]/g, '')
+    banned = banned.map(b => b.toLowerCase())
+    
+    paragraph.split(' ').forEach(word => {
+        if (wordsMap[word] === undefined) {
+            wordsMap[word] = 1
+            words.push(word)
+        } else {
+            wordsMap[word]++
+        }
+    })
+    
+    words.forEach(word => {
+        if (banned.findIndex(b => b === word) === -1 && wordsMap[word] > maxCount) {
+            res = word
+            maxCount = wordsMap[word]
+        }
+    })
+    return res
+};

algorithms/MostCommonWord/solution.py

@@ -0,0 +1,30 @@
+class Solution(object):
+    def mostCommonWord(self, paragraph, banned):
+        """
+        :type paragraph: str
+        :type banned: List[str]
+        :rtype: str
+        """
+        words_map = {}
+        words = []
+        paragraph = paragraph.lower()
+        paragraph = re.sub(r"[!?',;.]", '', paragraph)
+        
+        for i in range(len(banned)):
+            banned[i] = banned[i].lower()
+        
+        for word in paragraph.split(' '):
+            if words_map.get(word) == None:
+                words_map[word] = 1
+                words.append(word)
+            else:
+                words_map[word] += 1
+                
+        res = None
+        max_count = 0
+        for word in words:
+            if word not in banned and words_map[word] > max_count:
+                res = word
+                max_count = words_map[word]
+        
+        return res