Intersection of Two Arrays

Given two arrays, write a function to compute their intersection.

Example 1:

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]

Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]

Note:

• Each element in the result must be unique.

• The result can be in any order.

Solution

class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        // iterate through the first array and add it into set (to ensure unique values)
        // then iterate through second array and if the value is contained, it is intersection
        // than move data from set into array and retur it back
        Set<Integer> values = new HashSet<>();
        for (int num : nums1) {
            values.add(num);
        }
        Set<Integer> intersections = new HashSet<>();
        for (int num : nums2) {
            if (values.contains(num)) {
                intersections.add(num);
            }
        }
        int[] result = new int[intersections.size()];
        int index = 0;
        for (Integer num : intersections) {
            result[index++] = num;
        }
        return result;
    }
}