solves unique number of occurrences

Author: anishLearnsToCode

Diff for: README.md

@@ -317,7 +317,7 @@
 | 1189 | [Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons)                                                               |                                                        [![Java](assets/java.png)](src/MaximumNumberOfBalloons.java)                                                         |                                                                                                                                   |
 | 1196 | 🔒 [How Many Apples Can You Put into the Basket](https://leetcode.com/problems/how-many-apples-can-you-put-into-the-basket)                          |                                                                                                                                                                             |                                                                                                                                   |
 | 1200 | [Minimum Absolute Difference](https://leetcode.com/problems/minimum-absolute-difference)                                                             |                                                       [![Java](assets/java.png)](src/MinimumAbsoluteDifference.java)                                                        |                                                                                                                                   |
-| 1207 | [Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences)                                                           |                                                                                                                                                                             |                                                                                                                                   |
+| 1207 | [Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences)                                                           |                                                       [![Java](assets/java.png)](src/UniqueNumberOfOccurrences.java)                                                        |                                                                                                                                   |
 | 1213 | [Intersection of Three Sorted Arrays](https://leetcode.com/problems/intersection-of-three-sorted-arrays)                                             |                                                                                                                                                                             |                                                                                                                                   |
 | 1217 | [Play With Chips](https://leetcode.com/problems/play-with-chips)                                                                                     |                                                                                                                                                                             |                                                                                                                                   |
 | 1221 | [Split A String In Balanced Strings](https://leetcode.com/problems/split-a-string-in-balanced-strings)                                               |                                                                                                                                                                             |                                                                                                                                   |

Diff for: src/UniqueNumberOfOccurrences.java

@@ -0,0 +1,29 @@
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class UniqueNumberOfOccurrences {
+    public boolean uniqueOccurrences(int[] array) {
+        Map<Integer, Integer> frequencies = getFrequencies(array);
+        return areUnique(frequencies.values());
+    }
+
+    private Map<Integer, Integer> getFrequencies(int[] array) {
+        Map<Integer, Integer> frequencies = new HashMap<>();
+        for (int element : array) {
+            frequencies.put(element, frequencies.getOrDefault(element, 0) + 1);
+        }
+        return frequencies;
+    }
+
+    private boolean areUnique(Collection<Integer> numbers) {
+        Set<Integer> values = new HashSet<>();
+        for (int number : numbers) {
+            if (values.contains(number)) return false;
+            values.add(number);
+        }
+        return true;
+    }
+}