solves #2248: Intersection of Multiple Arrays

 in java

Author: anishLearnsToCode

README.md

@@ -730,7 +730,7 @@
 | 2236 | [Root Equals Sum of Children](https://leetcode.com/problems/root-equals-sum-of-children)                                                                               |                                                                                   [![Java](assets/java.png)](src/RootEqualsSumOfChildren.java)                                                                                   |                                                                                                                                   |
 | 2239 | [Find Closest Number to Zero](https://leetcode.com/problems/find-closest-number-to-zero)                                                                               |                                                                                   [![Java](assets/java.png)](src/FindClosestNumberToZero.java)                                                                                   |                                                                                                                                   |
 | 2243 | [Calculate Digit Sum of a String](https://leetcode.com/problems/calculate-digit-sum-of-a-string)                                                                       |                                                                                 [![Java](assets/java.png)](src/CalculateDigitSumOfAString.java)                                                                                  |                                                                                                                                   |
-| 2248 | [Intersection of Multiple Arrays](https://leetcode.com/problems/intersection-of-multiple-arrays)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2248 | [Intersection of Multiple Arrays](https://leetcode.com/problems/intersection-of-multiple-arrays)                                                                       |                                                                                  [![Java](assets/java.png)](src/IntersectionOfMultipleArrays.java)                                                                                   |                                                                                                                                   |
 | 2255 | [Count Prefixes of a Given String](https://leetcode.com/problems/count-prefixes-of-a-given-string)                                                                     |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2259 | [Remove Digit From Number to Maximize Result](https://leetcode.com/problems/remove-digit-from-number-to-maximize-result)                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2264 | [Largest 3-Same-Digit Number in String](https://leetcode.com/problems/largest-3-same-digit-number-in-string)                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |

src/IntersectionOfMultipleArrays.java

@@ -0,0 +1,41 @@
+// https://leetcode.com/problems/intersection-of-multiple-arrays
+// T: O()
+// S: O()
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class IntersectionOfMultipleArrays {
+    public List<Integer> intersection(int[][] nums) {
+        Set<Integer> set = setFrom(nums[0]);
+        for (int index = 1 ; index < nums.length ; index++) {
+            final Set<Integer> other = setFrom(nums[index]);
+            set = intersection(set, other);
+        }
+        final List<Integer> list = toList(set);
+        list.sort(Integer::compareTo);
+        return list;
+    }
+
+    private Set<Integer> setFrom(int[] array) {
+        final Set<Integer> set = new HashSet<>();
+        for (int element : array) {
+            set.add(element);
+        }
+        return set;
+    }
+
+    private List<Integer> toList(final Set<Integer> set) {
+        return new ArrayList<>(set);
+    }
+
+    private Set<Integer> intersection(Set<Integer> set1, Set<Integer> set2) {
+        final Set<Integer> result = new HashSet<>();
+        for (int element : set1) {
+            if (set2.contains(element)) result.add(element);
+        }
+        return result;
+    }
+}