solves uncommon words from two sentences

Author: anishLearnsToCode

README.md

@@ -1,7 +1,7 @@
 # LeetCode Algorithms
 
-![problems-solved](https://img.shields.io/badge/Problems%20Solved-195/2081-1f425f.svg)
-![problems-solved-java](https://img.shields.io/badge/Java-195/2081-1abc9c.svg)
+![problems-solved](https://img.shields.io/badge/Problems%20Solved-206/2081-1f425f.svg)
+![problems-solved-java](https://img.shields.io/badge/Java-206/2081-1abc9c.svg)
 ![problems-solved-python](https://img.shields.io/badge/Python-186/2081-1abc9c.svg)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 [![cp](https://img.shields.io/badge/also%20see-Competitve%20Programming-1f72ff.svg)](https://github.com/anishLearnsToCode/competitive-programming)
@@ -238,7 +238,7 @@
 | 874 | [Walking Robot Simulation](https://leetcode.com/problems/walking-robot-simulation) | |
 | 876 | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list) | [![Java](assets/java.png)](src/MiddleOfTheLinkedList.java) |
 | 883 | [Projection Area of 3D Shapes](https://leetcode.com/problems/projection-area-of-3d-shapes) | [![Java](assets/java.png)](src/ProjectionAreaOf3DShapes.java) |
-| 884 | [Uncommon Words from 2 Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences) | |
+| 884 | [Uncommon Words from 2 Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences) | [![Java](assets/java.png)](src/UncommonWordsFromTwoSentences.java) |
 | 888 | [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap) | |
 | 892 | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes) | |
 | 893 | [Groups of Special Equivalent Strings](https://leetcode.com/problems/groups-of-special-equivalent-strings) | |

src/UncommonWordsFromTwoSentences.java

@@ -0,0 +1,35 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class UncommonWordsFromTwoSentences {
+    public String[] uncommonFromSentences(String s1, String s2) {
+        final Map<String, Integer> sentence1Words = getWordFrequencies(s1);
+        final Map<String, Integer> sentence2Words = getWordFrequencies(s2);
+        final List<String> result = new ArrayList<>();
+        for (Map.Entry<String, Integer> entry : sentence1Words.entrySet()) {
+            if (entry.getValue() == 1 && !sentence2Words.containsKey(entry.getKey())) result.add(entry.getKey());
+        }
+        for (Map.Entry<String, Integer> entry : sentence2Words.entrySet()) {
+            if (entry.getValue() == 1 && !sentence1Words.containsKey(entry.getKey())) result.add(entry.getKey());
+        }
+        return result.toArray(new String[] {});
+    }
+
+    private Map<String, Integer> getWordFrequencies(String string) {
+        final Map<String, Integer> map = new HashMap<>();
+        StringBuilder word =new StringBuilder();
+        String s;
+        for (int index = 0 ; index < string.length() ; index++) {
+            if (string.charAt(index) == ' ') {
+                s = word.toString();
+                map.put(s, map.getOrDefault(s, 0) + 1);
+                word = new StringBuilder();
+            } else word.append(string.charAt(index));
+        }
+        s = word.toString();
+        map.put(s, map.getOrDefault(s, 0) + 1);
+        return map;
+    }
+}