solves #3162: Find the Number of Good Pairs I in java

Author: anishLearnsToCode

Diff for: README.md

@@ -913,7 +913,7 @@
 | 3146 | [Permutation Difference between Two Strings](https://leetcode.com/problems/permutation-difference-between-two-strings)                                                 |                                                                           [![Java](assets/java.png)](src/PermutationDifferenceBetweenTwoStrings.java)                                                                            |                                                                                                                                   |
 | 3151 | [Special Array I](https://leetcode.com/problems/special-array-i)                                                                                                       |                                                                                        [![Java](assets/java.png)](src/SpecialArrayI.java)                                                                                        |                                                                                                                                   |
 | 3158 | [Find the XOR of Numbers Which Appear Twice](https://leetcode.com/problems/find-the-xor-of-numbers-which-appear-twice)                                                 |                                                                             [![Java](assets/java.png)](src/FindTheXOROfNumbersWhichAppearTwice.java)                                                                             |                                                                                                                                   |
-| 3162 | [Find the Number of Good Pairs I](https://leetcode.com/problems/find-the-number-of-good-pairs-i)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 3162 | [Find the Number of Good Pairs I](https://leetcode.com/problems/find-the-number-of-good-pairs-i)                                                                       |                                                                                  [![Java](assets/java.png)](src/FindTheNumberOfGoodPairsI.java)                                                                                  |                                                                                                                                   |
 | 3168 | [Minimum Number of Chairs in a Waiting Room](https://leetcode.com/problems/minimum-number-of-chairs-in-a-waiting-room)                                                 |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 3173 | [Bitwise OR of Adjacent Elements](https://leetcode.com/problems/bitwise-or-of-adjacent-elements)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 3174 | [Clear Digits](https://leetcode.com/problems/clear-digits)                                                                                                             |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/FindTheNumberOfGoodPairsI.java

@@ -0,0 +1,50 @@
+// https://leetcode.com/problems/find-the-number-of-good-pairs-i
+// x = largest possible integer
+// T: O(n*sqrt(x) + m)
+// S: O(n + m)
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class FindTheNumberOfGoodPairsI {
+    public int numberOfPairs(int[] array1, int[] array2, int k) {
+        final Map<Integer, Integer> dividends = getDividendFrequencies(array1, k);
+        final Map<Integer, Integer> divisors = getElementFrequencies(array2);
+        int pairs = 0;
+
+        for (Map.Entry<Integer, Integer> entry : dividends.entrySet()) {
+            final int dividend = entry.getKey();
+            final int frequency = entry.getValue();
+
+            for (int i = 1 ; i * i <= dividend ; i++) {
+                if (dividend % i == 0) {
+                    pairs += frequency * divisors.getOrDefault(i, 0);
+                    if (i != dividend / i) {
+                        pairs += frequency * divisors.getOrDefault(dividend / i, 0);
+                    }
+                }
+            }
+        }
+
+        return pairs;
+    }
+
+    private static Map<Integer, Integer> getElementFrequencies(int[] array) {
+        final Map<Integer, Integer> frequencies = new HashMap<>();
+        for (int element : array) {
+            frequencies.put(element, frequencies.getOrDefault(element, 0) + 1);
+        }
+        return frequencies;
+    }
+
+    private static Map<Integer, Integer> getDividendFrequencies(int[] array, int k) {
+        final Map<Integer, Integer> frequencies = new HashMap<>();
+        for (int element : array) {
+            if (element % k == 0) {
+                int quotient = element / k;
+                frequencies.put(quotient, frequencies.getOrDefault(quotient, 0) + 1);
+            }
+        }
+        return frequencies;
+    }
+}