solves count common words with only one occurrence

Author: anishLearnsToCode

Diff for: README.md

@@ -493,8 +493,8 @@
 | 2062 | [Count Vowel Substrings of a String](https://leetcode.com/problems/count-vowel-substrings-of-a-string)                                                    |                                                          [![Java](assets/java.png)](src/CountVowelSubstringsOfAString.java)                                                          |                                                                                                                                   |
 | 2068 | [Check Whether Two Strings are Almost Equivalent](https://leetcode.com/problems/check-whether-two-strings-are-almost-equivalent)                          |                                                    [![Java](assets/java.png)](src/CheckWhetherTwoStringsAreAlmostEquivalent.java)                                                    |                                                                                                                                   |
 | 2073 | [Time Needed to Buy Tickets](https://leetcode.com/problems/time-needed-to-buy-tickets)                                                                    |                                                             [![Java](assets/java.png)](src/TimeNeededToBuyTickets.java)                                                              |                                                                                                                                   |
-| 2078 | [Two Furthest Houses With Different Colors](https://leetcode.com/problems/two-furthest-houses-with-different-colors)                                      |                                                        [![Java](assets/java.png)](src/TwoFurthestHousesWithDifferentColors.java)                                                         |                                                                                                                                   |
-| 2085 | [Count Common Words With One Occurrence](https://leetcode.com/problems/count-common-words-with-one-occurrence)                                            |                                                                                                                                                                                      |                                                                                                                                   |
+| 2078 | [Two Furthest Houses With Different Colors](https://leetcode.com/problems/two-furthest-houses-with-different-colors)                                      |                                                      [![Java](assets/java.png)](src/TwoFurthestHousesWithDifferentColors.java)                                                       |                                                                                                                                   |
+| 2085 | [Count Common Words With One Occurrence](https://leetcode.com/problems/count-common-words-with-one-occurrence)                                            |                                                        [![Java](assets/java.png)](src/CountCommonWordsWithOneOccurrence.java)                                                        |                                                                                                                                   |
 | 2089 | [Find Target Indices After Sorting Array](https://leetcode.com/problems/find-target-indices-after-sorting-array)                                          |                                                                                                                                                                                      |                                                                                                                                   |
 | 2094 | [Finding 3-Digit Even Numbers](https://leetcode.com/problems/finding-3-digit-even-numbers)                                                                |                                                                                                                                                                                      |                                                                                                                                   |
 | 2099 | [Find Subsequence of Length K With the Largest Sum](https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum)                      |                                                                                                                                                                                      |                                                                                                                                   |

Diff for: src/CountCommonWordsWithOneOccurrence.java

@@ -0,0 +1,28 @@
+// https://leetcode.com/problems/count-common-words-with-one-occurrence
+// T: O(|words1| + |words2|)
+// S: O(|words1| + |words2|)
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class CountCommonWordsWithOneOccurrence {
+    public int countWords(String[] words1, String[] words2) {
+        final Map<String, Integer> words1Frequency = getFrequencies(words1);
+        final Map<String, Integer> words2Frequency = getFrequencies(words2);
+        int words = 0;
+        for (Map.Entry<String, Integer> entry: words1Frequency.entrySet()) {
+            if (entry.getValue() == 1 && words2Frequency.getOrDefault(entry.getKey(), 0) == 1) {
+                words++;
+            }
+        }
+        return words;
+    }
+
+    private Map<String, Integer> getFrequencies(String[] array) {
+        final Map<String, Integer> frequencies = new HashMap<>();
+        for (String s : array) {
+            frequencies.put(s, frequencies.getOrDefault(s, 0) + 1);
+        }
+        return frequencies;
+    }
+}