LeetCode12|两个数组的交集

输入：nums1 = [1,2,2,1], nums2 = [2,2]
输出：[2]

 
import java.util.HashSet;

public class IntersectionTest {
    public static void main(String[] args) {
        int[] nums1 = {1, 2, 2, 1};
        int[] nums2 = {2, 2};
        int[] intersection = intersection(nums1, nums2);
        for (int j : intersection) {
            System.out.print(j + "\t");
        }
    }

    public static int[] intersection(int[] num1, int[] num2) {
        if (num1 == null || num1.length == 0 || num2 == null || num2.length == 0) {
            return new int[0];
        }
        HashSet<Integer> num1Set = new HashSet<>(num1.length);
        HashSet<Integer> num2Set = new HashSet<>(num2.length);
        for (Integer num : num1
        ) {
            num1Set.add(num);
        }
        for (Integer num : num2
        ) {
            num2Set.add(num);
        }
        num1Set.retainAll(num2Set);
        int[] result = new int[num1Set.size()];
        int i = 0;
        for (Integer integer : num1Set) {
            result[i++] = integer;
        }
        return result;
    }
}