Add solution #819

Author: JoshCrozier

solutions/0819-most-common-word.js

@@ -0,0 +1,27 @@
+/**
+ * 819. Most Common Word
+ * https://leetcode.com/problems/most-common-word/
+ * Difficulty: Easy
+ *
+ * Given a paragraph and a list of banned words, return the most frequent word that
+ * is not in the list of banned words.  It is guaranteed there is at least one word
+ * that isn't banned, and that the answer is unique.
+ *
+ * Words in the list of banned words are given in lowercase, and free of punctuation.
+ * Words in the paragraph are not case sensitive.  The answer is in lowercase.
+ */
+
+/**
+ * @param {string} paragraph
+ * @param {string[]} banned
+ * @return {string}
+ */
+var mostCommonWord = function(paragraph, banned) {
+  const occurrences = new Map();
+  paragraph.toLowerCase().replace(/[^\w\s]/g, ' ').split(/\s+/).forEach(word => {
+    if (!banned.includes(word)) {
+      occurrences.set(word, occurrences.has(word) ? occurrences.get(word) + 1 : 1);
+    }
+  });
+  return Array.from(occurrences).sort((a, b) => b[1] - a[1])[0][0];
+};