Is Intersection of Two Arrays easy or hard?

Intersection of Two Arrays is classified as an Easy problem. It mainly tests familiarity with sets, basic array traversal, and simple algorithmic optimization.

Intersection of Two Arrays Python/Java solution

In Python, the solution often uses the built-in set type for O(1) lookups. In Java, developers typically use HashSet to store elements and check membership while scanning the second array.

How to solve Intersection of Two Arrays in O(n)?

Use a hash set to store elements from the first array. Iterate through the second array and perform constant-time set lookups. If the element exists, insert it into a result set to keep values unique. This produces an O(m + n) solution.

What is the best approach for Intersection of Two Arrays?

The hash set approach is generally considered the best solution. Insert elements of one array into a set and check membership while scanning the second array. This produces the intersection in O(m + n) time with O(m + n) space and avoids duplicate results.

Is Intersection of Two Arrays asked at Google/Amazon/Meta?

Intersection-style array problems frequently appear in interviews at companies like Google, Amazon, and Meta. Variants test knowledge of hash tables, two pointers, and efficient duplicate handling.

What data structure is used in Intersection of Two Arrays?

The most common data structure is a hash set (or hash table). It allows constant-time membership checks and automatically handles duplicates, which simplifies the intersection logic.

What is the time complexity of Intersection of Two Arrays?

The optimal solution runs in O(m + n) time using a hash set, where m and n are the lengths of the two arrays. Sorting-based solutions take O(m log m + n log n) because of the sorting step before applying two pointers.

Description Solution Video 4:23

349. Intersection of Two Arrays

Easy78.2% acceptance16 companies

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order.

Example 1:

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

Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]
Explanation: [4,9] is also accepted.

Constraints:

1 <= nums1.length, nums2.length <= 1000
0 <= nums1[i], nums2[i] <= 1000

Asked at 16 companies

MongoDB Criteo Wix Two Sigma Accenture Capgemini

Google Amazon Microsoft Meta Bloomberg JPMorgan Chase

+4 more

Apple

Infosys Zoho Yandex

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349. Intersection of Two Arrays

Asked at 16 companies

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