Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Rubrik. 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: Maximize Subarray Sum After Removing All Occurrences of One Element

You are given an integer array nums. You can do the following operation on the array at most once: Choose any integer x such that nums remains non-empty on removing all occurrences of x. Remove all occurrences of x from the array. Return the maximum subarray sum across all possible resulting arrays. Example 1: Input: nums = [-3,2,-2,-1,3,-2,3] Output: 7 Explanation: We can have the following arrays after at most one operation: The original array is nums = [-3, 2, -2, -1, 3, -2, 3]. The maximum subarray sum is 3 + (-2) + 3 = 4. Deleting all occurences of x = -3 results in nums = [2, -2, -1, 3, -2, 3]. The maximum subarray sum is 3 + (-2) + 3 = 4. Deleting all occurences of x = -2 results in nums = [-3, 2, -1, 3, 3]. The maximum subarray sum is 2 + (-1) + 3 + 3 = 7. Deleting all occurences of x = -1 results in nums = [-3, 2, -2, 3, -2, 3]. The maximum subarray sum is 3 + (-2) + 3 = 4. Deleting all occurences of x = 3 results in nums = [-3, 2, -2, -1, -2]. The maximum subarray sum is 2. The output is max(4, 4, 7, 4, 2) = 7. Example 2: Input: nums = [1,2,3,4] Output: 10 Explanation: It is optimal to not perform any operations. Constraints: 1 <= nums.length <= 105 -106 <= nums[i] <= 106

Topics: Array, Dynamic Programming, Segment Tree

Problem #2: Manhattan Distances of All Arrangements of Pieces

You are given three integers m, n, and k. There is a rectangular grid of size m × n containing k identical pieces. Return the sum of Manhattan distances between every pair of pieces over all valid arrangements of pieces. A valid arrangement is a placement of all k pieces on the grid with at most one piece per cell. Since the answer may be very large, return it modulo 109 + 7. The Manhattan Distance between two cells (xi, yi) and (xj, yj) is |xi - xj| + |yi - yj|. Example 1: Input: m = 2, n = 2, k = 2 Output: 8 Explanation: The valid arrangements of pieces on the board are: In the first 4 arrangements, the Manhattan distance between the two pieces is 1. In the last 2 arrangements, the Manhattan distance between the two pieces is 2. Thus, the total Manhattan distance across all valid arrangements is 1 + 1 + 1 + 1 + 2 + 2 = 8. Example 2: Input: m = 1, n = 4, k = 3 Output: 20 Explanation: The valid arrangements of pieces on the board are: The first and last arrangements have a total Manhattan distance of 1 + 1 + 2 = 4. The middle two arrangements have a total Manhattan distance of 1 + 2 + 3 = 6. The total Manhattan distance between all pairs of pieces across all arrangements is 4 + 6 + 6 + 4 = 20. Constraints: 1 <= m, n <= 105 2 <= m n <= 105 2 <= k <= m n

Topics: Math, Combinatorics

Problem #3: 4Sum

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that: 0 <= a, b, c, d < n a, b, c, and d are distinct. nums[a] + nums[b] + nums[c] + nums[d] == target You may return the answer in any order. Example 1: Input: nums = [1,0,-1,0,-2,2], target = 0 Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]] Example 2: Input: nums = [2,2,2,2,2], target = 8 Output: [[2,2,2,2]] Constraints: 1 <= nums.length <= 200 -109 <= nums[i] <= 109 -109 <= target <= 109

Topics: Array, Two Pointers, Sorting

Problem #4: Insert Delete GetRandom O(1)

Implement the RandomizedSet class: RandomizedSet() Initializes the RandomizedSet object. bool insert(int val) Inserts an item val into the set if not present. Returns true if the item was not present, false otherwise. bool remove(int val) Removes an item val from the set if present. Returns true if the item was present, false otherwise. int getRandom() Returns a random element from the current set of elements (it's guaranteed that at least one element exists when this method is called). Each element must have the same probability of being returned. You must implement the functions of the class such that each function works in average O(1) time complexity. Example 1: Input ["RandomizedSet", "insert", "remove", "insert", "getRandom", "remove", "insert", "getRandom"] [[], [1], [2], [2], [], [1], [2], []] Output [null, true, false, true, 2, true, false, 2] Explanation RandomizedSet randomizedSet = new RandomizedSet(); randomizedSet.insert(1); // Inserts 1 to the set. Returns true as 1 was inserted successfully. randomizedSet.remove(2); // Returns false as 2 does not exist in the set. randomizedSet.insert(2); // Inserts 2 to the set, returns true. Set now contains [1,2]. randomizedSet.getRandom(); // getRandom() should return either 1 or 2 randomly. randomizedSet.remove(1); // Removes 1 from the set, returns true. Set now contains [2]. randomizedSet.insert(2); // 2 was already in the set, so return false. randomizedSet.getRandom(); // Since 2 is the only number in the set, getRandom() will always return 2. Constraints: -231 <= val <= 231 - 1 At most 2 * 105 calls will be made to insert, remove, and getRandom. There will be at least one element in the data structure when getRandom is called.

Topics: Array, Hash Table, Math, Design, Randomized

Problem #5: Stamping the Grid

You are given an m x n binary matrix grid where each cell is either 0 (empty) or 1 (occupied). You are then given stamps of size stampHeight x stampWidth. We want to fit the stamps such that they follow the given restrictions and requirements: Cover all the empty cells. Do not cover any of the occupied cells. We can put as many stamps as we want. Stamps can overlap with each other. Stamps are not allowed to be rotated. Stamps must stay completely inside the grid. Return true if it is possible to fit the stamps while following the given restrictions and requirements. Otherwise, return false. Example 1: Input: grid = [[1,0,0,0],[1,0,0,0],[1,0,0,0],[1,0,0,0],[1,0,0,0]], stampHeight = 4, stampWidth = 3 Output: true Explanation: We have two overlapping stamps (labeled 1 and 2 in the image) that are able to cover all the empty cells. Example 2: Input: grid = [[1,0,0,0],[0,1,0,0],[0,0,1,0],[0,0,0,1]], stampHeight = 2, stampWidth = 2 Output: false Explanation: There is no way to fit the stamps onto all the empty cells without the stamps going outside the grid. Constraints: m == grid.length n == grid[r].length 1 <= m, n <= 105 1 <= m n <= 2 105 grid[r][c] is either 0 or 1. 1 <= stampHeight, stampWidth <= 105

Topics: Array, Greedy, Matrix, Prefix Sum