Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Darwinbox. 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: Scramble String

We can scramble a string s to get a string t using the following algorithm: If the length of the string is 1, stop. If the length of the string is > 1, do the following: Split the string into two non-empty substrings at a random index, i.e., if the string is s, divide it to x and y where s = x + y. Randomly decide to swap the two substrings or to keep them in the same order. i.e., after this step, s may become s = x + y or s = y + x. Apply step 1 recursively on each of the two substrings x and y. Given two strings s1 and s2 of the same length, return true if s2 is a scrambled string of s1, otherwise, return false. Example 1: Input: s1 = "great", s2 = "rgeat" Output: true Explanation: One possible scenario applied on s1 is: "great" --> "gr/eat" // divide at random index. "gr/eat" --> "gr/eat" // random decision is not to swap the two substrings and keep them in order. "gr/eat" --> "g/r / e/at" // apply the same algorithm recursively on both substrings. divide at random index each of them. "g/r / e/at" --> "r/g / e/at" // random decision was to swap the first substring and to keep the second substring in the same order. "r/g / e/at" --> "r/g / e/ a/t" // again apply the algorithm recursively, divide "at" to "a/t". "r/g / e/ a/t" --> "r/g / e/ a/t" // random decision is to keep both substrings in the same order. The algorithm stops now, and the result string is "rgeat" which is s2. As one possible scenario led s1 to be scrambled to s2, we return true. Example 2: Input: s1 = "abcde", s2 = "caebd" Output: false Example 3: Input: s1 = "a", s2 = "a" Output: true Constraints: s1.length == s2.length 1 <= s1.length <= 30 s1 and s2 consist of lowercase English letters.

Topics: String, Dynamic Programming

Problem #2: Number of Great Partitions

You are given an array nums consisting of positive integers and an integer k. Partition the array into two ordered groups such that each element is in exactly one group. A partition is called great if the sum of elements of each group is greater than or equal to k. Return the number of distinct great partitions. Since the answer may be too large, return it modulo 109 + 7. Two partitions are considered distinct if some element nums[i] is in different groups in the two partitions. Example 1: Input: nums = [1,2,3,4], k = 4 Output: 6 Explanation: The great partitions are: ([1,2,3], [4]), ([1,3], [2,4]), ([1,4], [2,3]), ([2,3], [1,4]), ([2,4], [1,3]) and ([4], [1,2,3]). Example 2: Input: nums = [3,3,3], k = 4 Output: 0 Explanation: There are no great partitions for this array. Example 3: Input: nums = [6,6], k = 2 Output: 2 Explanation: We can either put nums[0] in the first partition or in the second partition. The great partitions will be ([6], [6]) and ([6], [6]). Constraints: 1 <= nums.length, k <= 1000 1 <= nums[i] <= 109

Topics: Array, Dynamic Programming