solves logest common harmonious subsequence

Author: anishLearnsToCode

README.md

@@ -155,7 +155,7 @@
 | 581 | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray) | Medium | [![Java](assets/java.png)](src/ShortestUnsortedContinuousSubarray.java) [![Python](assets/python.png)](python/shortest_continuous_unsorted_subarray.py) |
 | 589 | [N-Ary Tree Preorder Traversal](https://leetcode.com/problems/n-ary-tree-preorder-traversal) | Easy | [![Java](assets/java.png)](src/NArayTreePreOrderTraversal.java) [![Python](assets/python.png)](python/n_ary_tree_preorder_traversal.py) |
 | 590 | [N-Ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal) | Easy | [![Java](assets/java.png)](src/NAryTreePostorderTraversal.java) [![Python](assets/python.png)](python/n_ary_tree_postorder_traversal.py) |
-| 594 | [Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence) | Easy | |
+| 594 | [Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence) | Easy | [![Java](assets/java.png)](src/LongestHarmoniousSubsequence.java) [![Python](assets/python.png)](python/longest_harmonious_subequence.py) |
 | 598 | [Range Addition II](https://leetcode.com/problems/range-addition-ii) | Easy | |
 | 599 | [Minimum Index Sum of 2 Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists) | Easy | |
 | 604 | [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator) | Easy | |

python/longest_harmonious_subequence.py

@@ -0,0 +1,15 @@
+from collections import Counter
+from typing import List
+
+
+class Solution:
+    def findLHS(self, array: List[int]) -> int:
+        frequencies = Counter(array)
+        result = 0
+        for value, frequency in frequencies.items():
+            result = max(
+                result,
+                frequencies.get(value - 1) + frequency if value - 1 in frequencies else 0,
+                frequencies.get(value + 1) + frequency if value + 1 in frequencies else 0
+            )
+        return result

src/LongestHarmoniousSubsequence.java

@@ -0,0 +1,26 @@
+import java.util.HashMap;
+import java.util.Map;
+
+public class LongestHarmoniousSubsequence {
+    public int findLHS(int[] array) {
+        Map<Integer, Integer> frequencies = getFrequencies(array);
+        int value, frequency, result = 0;
+        for (Map.Entry<Integer, Integer> entry : frequencies.entrySet()) {
+            value = entry.getKey();
+            frequency = entry.getValue();
+            result = Math.max(result, Math.max(
+                    frequencies.containsKey(value - 1) ? frequency + frequencies.get(value - 1) : 0,
+                    frequencies.containsKey(value + 1) ? frequency + frequencies.get(value + 1) : 0
+            ));
+        }
+        return result;
+    }
+
+    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;
+    }
+}