add 819

fishercoder1534 · fishercoder1534 · commit 4a8f99eab319 · 2018-04-15T16:33:18.000-07:00
diff --git a/README.md b/README.md
@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|819|[Most Common Word](https://leetcode.com/problems/most-common-word/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_819.java) | O(m+n) | O(n) | |Easy| HashMap
 |811|[Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_811.java) | O(n) | O(n) | |Easy| HashMap
 |806|[Number of Lines To Write String](https://leetcode.com/problems/number-of-lines-to-write-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_806.java) | O(n) | O(1) | |Easy|
 |804|[Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_804.java) | O(S) | O(S) | |Easy|
diff --git a/src/main/java/com/fishercoder/solutions/_819.java b/src/main/java/com/fishercoder/solutions/_819.java
@@ -0,0 +1,60 @@
+package com.fishercoder.solutions;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * 819. Most Common Word
+
+ 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.
+
+ Example:
+ 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.
+
+ Note:
+
+ 1 <= paragraph.length <= 1000.
+ 1 <= banned.length <= 100.
+ 1 <= banned[i].length <= 10.
+ The answer is unique, and written in lowercase (even if its occurrences in paragraph may have uppercase symbols, and even if it is a proper noun.)
+ paragraph only consists of letters, spaces, or the punctuation symbols !?',;.
+ Different words in paragraph are always separated by a space.
+ There are no hyphens or hyphenated words.
+ Words only consist of letters, never apostrophes or other punctuation symbols.
+ */
+public class _819 {
+  public static class Solution1 {
+    public String mostCommonWord(String paragraph, String[] banned) {
+      Set<String> bannedSet = new HashSet(Arrays.asList(banned));
+      String[] words = paragraph.replaceAll("[^a-zA-Z ]", "").toLowerCase().split("\\s+");
+      Map<String, Integer> map = new HashMap<>();
+      Arrays.stream(words)
+          .filter(word -> !bannedSet.contains(word))
+          .forEach(word -> map.put(word, map.getOrDefault(word, 0) + 1));
+      String result = "";
+      int freq = 0;
+      for (String key : map.keySet()) {
+        if (map.get(key) > freq) {
+          result = key;
+          freq = map.get(key);
+        }
+      }
+      return result;
+    }
+  }
+}
diff --git a/src/test/java/com/fishercoder/_819Test.java b/src/test/java/com/fishercoder/_819Test.java
@@ -0,0 +1,25 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._819;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _819Test {
+  private static _819.Solution1 solution1;
+  private static String[] banned;
+
+  @BeforeClass
+  public static void setup() {
+    solution1 = new _819.Solution1();
+  }
+
+  @Test
+  public void test1() {
+    banned = new String[] {"hit"};
+    assertEquals("ball",
+        solution1.mostCommonWord("Bob hit a ball, the hit BALL flew far after it was hit.",
+            banned));
+  }
+}
