leetcode/java/349_Intersection_of_Two_Arrays.java at master · cphysics/leetcode

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https://leetcode.com/problems/intersection-of-two-arrays/

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

Convert one array to a set. For each element in other array, if in first array set add to intersection. Convert

intersection to array.

Time - O(m + n)

Space - O(m + n)

public class Solution {

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

Set<Integer> nums1Set = new HashSet();

for (int n : nums1) {

nums1Set.add(n);

}

Set<Integer> intersect = new HashSet();

for (int n : nums2) {

if (nums1Set.contains(n)) {

intersect.add(n);

}

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

int index = 0;

for(int i : intersect) {

result[index++] = i;

}

return result;

}