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547 · Intersection of Two Arrays - LintCode

# Description

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

  • Each element in the result must be unique.

# Example

Example 1:

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

Example 2:

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

# code

public class Solution {
    /**
     * @param nums1: an integer array
     * @param nums2: an integer array
     * @return: an integer array
     *          we will sort your return value in output
     */
    public int[] intersection(int[] nums1, int[] nums2) {
        if (nums1 == null || nums1.length == 0 || nums2== null || nums2.length == 0) {
            return new int[]{};
        }
        Arrays.sort(nums1);
        Arrays.sort(nums2);
        List<Integer> list = new ArrayList<>();
        int p1 = 0;
        int p2 = 0;
        while (p1 < nums1.length && p2 < nums2.length) {
            if (nums1[p1] == nums2[p2]) {
                if (list.size() == 0 || list.get(list.size() - 1) != nums1[p1]) {
                    list.add(nums1[p1]);
                }
                p1++;
                p2++;
            } else if (nums1[p1] < nums2[p2]) {
                p1++;
            } else {
                p2++;
            }
        }
        int[] res = new int[list.size()];
        for (int i = 0; i < list.size(); i++) {
            res[i] = list.get(i);
        }
        return res;
    }
}