leetcode-349-easy

Intersection of Two Arrays

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order.

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]
Explanation: [4,9] is also accepted.
Constraints:

1 <= nums1.length, nums2.length <= 1000
0 <= nums1[i], nums2[i] <= 1000

思路一：用 set 记录存储过的值，对比前后数组即可求解

    public int[] intersection(int[] nums1, int[] nums2) {
        Set<Integer> set = new HashSet<>();

        for (int num : nums1) {
            set.add(num);
        }

        Set<Integer> result = new HashSet<>();
        for (int num : nums2) {
            if (set.contains(num)) {
                result.add(num);
            }
        }

        int[] resulttArr = new int[result.size()];
        Integer[] integers = result.toArray(new Integer[]{});
        for (int i = 0; i < integers.length; i++) {
            resulttArr[i] = integers[i];
        }

        return resulttArr;
    }