Problem
Given two integer arrays, return their intersection. Each element in the result must be unique.
Example
Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]Solution
Convert both arrays to sets and find intersection.
def intersection(nums1, nums2):
return list(set(nums1) & set(nums2))function intersection(nums1, nums2) {
const set1 = new Set(nums1);
return [...new Set(nums2.filter(x => set1.has(x)))];
}vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
unordered_set<int> set1(nums1.begin(), nums1.end());
unordered_set<int> result;
for (int x : nums2) {
if (set1.count(x)) result.insert(x);
}
return vector<int>(result.begin(), result.end());
}public int[] intersection(int[] nums1, int[] nums2) {
Set<Integer> set1 = new HashSet<>();
for (int x : nums1) set1.add(x);
Set<Integer> result = new HashSet<>();
for (int x : nums2) if (set1.contains(x)) result.add(x);
return result.stream().mapToInt(Integer::intValue).toArray();
}Complexity
- Time: O(n + m)
- Space: O(n + m)
Explanation
Sets give O(1) lookups. Convert one array to a set, scan the other for matches, dedupe via another set.
Comments
Join the discussion. Got a question, found an issue, or want to share your experience?