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/**

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

*

* Example:

* Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].

*

* Note:

* Each element in the result must be unique.

* The result can be in any order.

*/

import java.util.Set;

import java.util.HashSet;

public class IntersectionOfTwoArrays349 {

public static int[] intersection(int[] nums1, int[] nums2) {

if (nums1 == null || nums1.length == 0 ||

nums2 == null || nums2.length == 0) return new int[]{};

Set<Integer> setNums1 = new HashSet<>();

for (int i1: nums1) {

setNums1.add(i1);

}

Set<Integer> resSet = new HashSet<>();

for (int i2: nums2) {

if (setNums1.contains(i2)) {

resSet.add(i2);

}

}

int[] res = new int[resSet.size()];

int i = 0;

for (Integer resInt: resSet) {

res[i++] = (int) resInt;

}

return res;

}

/**

* https://leetcode.com/problems/intersection-of-two-arrays/discuss/81969/Three-Java-Solutions

*/

public int[] intersection2(int[] nums1, int[] nums2) {

Set<Integer> set = new HashSet<>();

Arrays.sort(nums1);

Arrays.sort(nums2);

int i = 0;

int j = 0;

while (i < nums1.length && j < nums2.length) {

if (nums1[i] < nums2[j]) {

i++;

} else if (nums1[i] > nums2[j]) {

j++;

} else {

set.add(nums1[i]);

i++;

j++;

}

}

int[] result = new int[set.size()];

int k = 0;

for (Integer num : set) {

result[k++] = num;

}

return result;

}

}