solves #2206: Divide Array Into Equal Pairs in java

Author: anishLearnsToCode

Diff for: README.md

@@ -719,7 +719,7 @@
 | 2190 | [Most Frequent Number Following Key In an Array](https://leetcode.com/problems/most-frequent-number-following-key-in-an-array)                                         |                                                                           [![Java](assets/java.png)](src/MostFrequentNumberFollowingKeyInAnArray.java)                                                                           |                                                                                                                                   |
 | 2194 | [Cells in a Range on an Excel Sheet](https://leetcode.com/problems/cells-in-a-range-on-an-excel-sheet)                                                                 |                                                                                 [![Java](assets/java.png)](src/CellsInARangeOnAnExcelSheet.java)                                                                                 |                                                                                                                                   |
 | 2200 | [Find All K-Distant Indices in an Array](https://leetcode.com/problems/find-all-k-distant-indices-in-an-array)                                                         |                                                                               [![Java](assets/java.png)](src/FindAllKDistantIndicesInAnArray.java)                                                                               |                                                                                                                                   |
-| 2206 | [Divide Array Into Equal Pairs](https://leetcode.com/problems/divide-array-into-equal-pairs)                                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2206 | [Divide Array Into Equal Pairs](https://leetcode.com/problems/divide-array-into-equal-pairs)                                                                           |                                                                                  [![Java](assets/java.png)](src/DivideArrayIntoEqualPairs.java)                                                                                  |                                                                                                                                   |
 | 2210 | [Count Hills and Valleys in an Array](https://leetcode.com/problems/count-hills-and-valleys-in-an-array)                                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2215 | [Find the Difference of Two Arrays](https://leetcode.com/problems/find-the-difference-of-two-arrays)                                                                   |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2220 | [Minimum Bit Flips to Convert Number](https://leetcode.com/problems/minimum-bit-flips-to-convert-number)                                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/DivideArrayIntoEqualPairs.java

@@ -0,0 +1,28 @@
+// https://leetcode.com/problems/divide-array-into-equal-pairs
+// T: O(N)
+// S: O(N)
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class DivideArrayIntoEqualPairs {
+    public static boolean divideArray(int[] array) {
+        final Map<Integer, Integer> frequencies = getFrequencies(array);
+        return allFrequenciesAreEven(frequencies);
+    }
+
+    private static boolean allFrequenciesAreEven(Map<Integer, Integer> frequencies) {
+        for (int frequency : frequencies.values()) {
+            if (frequency % 2 == 1) return false;
+        }
+        return true;
+    }
+
+    private static Map<Integer, Integer> getFrequencies(int[] array) {
+        final Map<Integer, Integer> result = new HashMap<>();
+        for (int element : array) {
+            result.put(element, result.getOrDefault(element, 0) + 1);
+        }
+        return result;
+    }
+}