Introduction

In this blog post, we'll share the most commonly asked coding interview questions at InMobi. 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: Partition Labels

You are given a string s. We want to partition the string into as many parts as possible so that each letter appears in at most one part. For example, the string "ababcc" can be partitioned into ["abab", "cc"], but partitions such as ["aba", "bcc"] or ["ab", "ab", "cc"] are invalid. Note that the partition is done so that after concatenating all the parts in order, the resultant string should be s. Return a list of integers representing the size of these parts. Example 1: Input: s = "ababcbacadefegdehijhklij" Output: [9,7,8] Explanation: The partition is "ababcbaca", "defegde", "hijhklij". This is a partition so that each letter appears in at most one part. A partition like "ababcbacadefegde", "hijhklij" is incorrect, because it splits s into less parts. Example 2: Input: s = "eccbbbbdec" Output: [10] Constraints: 1 <= s.length <= 500 s consists of lowercase English letters.

Topics: Hash Table, Two Pointers, String, Greedy

Problem #2: Maximum Number of Robots Within Budget

You have n robots. You are given two 0-indexed integer arrays, chargeTimes and runningCosts, both of length n. The ith robot costs chargeTimes[i] units to charge and costs runningCosts[i] units to run. You are also given an integer budget. The total cost of running k chosen robots is equal to max(chargeTimes) + k sum(runningCosts), where max(chargeTimes) is the largest charge cost among the k robots and sum(runningCosts) is the sum of running costs among the k robots. Return the maximum number of consecutive robots you can run such that the total cost does not exceed budget. Example 1: Input: chargeTimes = [3,6,1,3,4], runningCosts = [2,1,3,4,5], budget = 25 Output: 3 Explanation: It is possible to run all individual and consecutive pairs of robots within budget. To obtain answer 3, consider the first 3 robots. The total cost will be max(3,6,1) + 3 sum(2,1,3) = 6 + 3 6 = 24 which is less than 25. It can be shown that it is not possible to run more than 3 consecutive robots within budget, so we return 3. Example 2: Input: chargeTimes = [11,12,19], runningCosts = [10,8,7], budget = 19 Output: 0 Explanation: No robot can be run that does not exceed the budget, so we return 0. Constraints: chargeTimes.length == runningCosts.length == n 1 <= n <= 5 104 1 <= chargeTimes[i], runningCosts[i] <= 105 1 <= budget <= 1015

Topics: Array, Binary Search, Queue, Sliding Window, Heap (Priority Queue), Prefix Sum, Monotonic Queue

Problem #3: Redundant Connection

In this problem, a tree is an undirected graph that is connected and has no cycles. You are given a graph that started as a tree with n nodes labeled from 1 to n, with one additional edge added. The added edge has two different vertices chosen from 1 to n, and was not an edge that already existed. The graph is represented as an array edges of length n where edges[i] = [ai, bi] indicates that there is an edge between nodes ai and bi in the graph. Return an edge that can be removed so that the resulting graph is a tree of n nodes. If there are multiple answers, return the answer that occurs last in the input. Example 1: Input: edges = [[1,2],[1,3],[2,3]] Output: [2,3] Example 2: Input: edges = [[1,2],[2,3],[3,4],[1,4],[1,5]] Output: [1,4] Constraints: n == edges.length 3 <= n <= 1000 edges[i].length == 2 1 <= ai < bi <= edges.length ai != bi There are no repeated edges. The given graph is connected.

Topics: Depth-First Search, Breadth-First Search, Union Find, Graph

Problem #4: Longest Valid Parentheses

Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring. Example 1: Input: s = "(()" Output: 2 Explanation: The longest valid parentheses substring is "()". Example 2: Input: s = ")()())" Output: 4 Explanation: The longest valid parentheses substring is "()()". Example 3: Input: s = "" Output: 0 Constraints: 0 <= s.length <= 3 * 104 s[i] is '(', or ')'.

Topics: String, Dynamic Programming, Stack