Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Hubspot. If you don't have months to study for your interviews, you can use AI tools like Chatmagic to generate solutions quickly and efficiently - helping you pass the interviews and get the job offer!

Problem #1: Merge Sorted Array

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively. Merge nums1 and nums2 into a single array sorted in non-decreasing order. The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n. Example 1: Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3 Output: [1,2,2,3,5,6] Explanation: The arrays we are merging are [1,2,3] and [2,5,6]. The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1. Example 2: Input: nums1 = [1], m = 1, nums2 = [], n = 0 Output: [1] Explanation: The arrays we are merging are [1] and []. The result of the merge is [1]. Example 3: Input: nums1 = [0], m = 0, nums2 = [1], n = 1 Output: [1] Explanation: The arrays we are merging are [] and [1]. The result of the merge is [1]. Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1. Constraints: nums1.length == m + n nums2.length == n 0 <= m, n <= 200 1 <= m + n <= 200 -109 <= nums1[i], nums2[j] <= 109 Follow up: Can you come up with an algorithm that runs in O(m + n) time?

Topics: Array, Two Pointers, Sorting

Problem #2: Maximum Number of Occurrences of a Substring

Given a string s, return the maximum number of occurrences of any substring under the following rules: The number of unique characters in the substring must be less than or equal to maxLetters. The substring size must be between minSize and maxSize inclusive. Example 1: Input: s = "aababcaab", maxLetters = 2, minSize = 3, maxSize = 4 Output: 2 Explanation: Substring "aab" has 2 occurrences in the original string. It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize). Example 2: Input: s = "aaaa", maxLetters = 1, minSize = 3, maxSize = 3 Output: 2 Explanation: Substring "aaa" occur 2 times in the string. It can overlap. Constraints: 1 <= s.length <= 105 1 <= maxLetters <= 26 1 <= minSize <= maxSize <= min(26, s.length) s consists of only lowercase English letters.

Topics: Hash Table, String, Sliding Window

Problem #3: Merge Intervals

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input. Example 1: Input: intervals = [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6]. Example 2: Input: intervals = [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considered overlapping. Constraints: 1 <= intervals.length <= 104 intervals[i].length == 2 0 <= starti <= endi <= 104

Topics: Array, Sorting

Problem #4: Merge Two Sorted Lists

You are given the heads of two sorted linked lists list1 and list2. Merge the two lists into one sorted list. The list should be made by splicing together the nodes of the first two lists. Return the head of the merged linked list. Example 1: Input: list1 = [1,2,4], list2 = [1,3,4] Output: [1,1,2,3,4,4] Example 2: Input: list1 = [], list2 = [] Output: [] Example 3: Input: list1 = [], list2 = [0] Output: [0] Constraints: The number of nodes in both lists is in the range [0, 50]. -100 <= Node.val <= 100 Both list1 and list2 are sorted in non-decreasing order.

Topics: Linked List, Recursion

Problem #5: Two Sum

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order. Example 1: Input: nums = [2,7,11,15], target = 9 Output: [0,1] Explanation: Because nums[0] + nums[1] == 9, we return [0, 1]. Example 2: Input: nums = [3,2,4], target = 6 Output: [1,2] Example 3: Input: nums = [3,3], target = 6 Output: [0,1] Constraints: 2 <= nums.length <= 104 -109 <= nums[i] <= 109 -109 <= target <= 109 Only one valid answer exists. Follow-up: Can you come up with an algorithm that is less than O(n2) time complexity?

Topics: Array, Hash Table

Problem #7: Find the K-Sum of an Array

You are given an integer array nums and a positive integer k. You can choose any subsequence of the array and sum all of its elements together. We define the K-Sum of the array as the kth largest subsequence sum that can be obtained (not necessarily distinct). Return the K-Sum of the array. A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements. Note that the empty subsequence is considered to have a sum of 0. Example 1: Input: nums = [2,4,-2], k = 5 Output: 2 Explanation: All the possible subsequence sums that we can obtain are the following sorted in decreasing order: - 6, 4, 4, 2, 2, 0, 0, -2. The 5-Sum of the array is 2. Example 2: Input: nums = [1,-2,3,4,-10,12], k = 16 Output: 10 Explanation: The 16-Sum of the array is 10. Constraints: n == nums.length 1 <= n <= 105 -109 <= nums[i] <= 109 1 <= k <= min(2000, 2n)

Topics: Array, Sorting, Heap (Priority Queue)