# Top 3 Moloco Coding Interview Questions from 2025


# Introduction
In this blog post, we'll share the most commonly asked coding interview questions at Moloco.  If you don't have months to study for your interviews, you can use AI tools like [Chatmagic](https://www.chatmagic.app) to generate solutions quickly and efficiently - helping you pass the interviews and get the job offer!

	
# Problem #1: [Longest String Chain](https://leetcode.com/problems/longest-string-chain)
> You are given an array of words where each word consists of lowercase English letters. wordA is a predecessor of wordB if and only if we can insert exactly one letter anywhere in wordA without changing the order of the other characters to make it equal to wordB.  For example, "abc" is a predecessor of "abac", while "cba" is not a predecessor of "bcad".  A word chain is a sequence of words [word1, word2, ..., wordk] with k >= 1, where word1 is a predecessor of word2, word2 is a predecessor of word3, and so on. A single word is trivially a word chain with k == 1. Return the length of the longest possible word chain with words chosen from the given list of words.   Example 1:  Input: words = ["a","b","ba","bca","bda","bdca"] Output: 4 Explanation: One of the longest word chains is ["a","ba","bda","bdca"].  Example 2:  Input: words = ["xbc","pcxbcf","xb","cxbc","pcxbc"] Output: 5 Explanation: All the words can be put in a word chain ["xb", "xbc", "cxbc", "pcxbc", "pcxbcf"].  Example 3:  Input: words = ["abcd","dbqca"] Output: 1 Explanation: The trivial word chain ["abcd"] is one of the longest word chains. ["abcd","dbqca"] is not a valid word chain because the ordering of the letters is changed.    Constraints:  1 <= words.length <= 1000 1 <= words[i].length <= 16 words[i] only consists of lowercase English letters.  

Topics: Array, Hash Table, Two Pointers, String, Dynamic Programming, Sorting


# Problem #2: [Single Element in a Sorted Array](https://leetcode.com/problems/single-element-in-a-sorted-array)
> You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once. Return the single element that appears only once. Your solution must run in O(log n) time and O(1) space.   Example 1: Input: nums = [1,1,2,3,3,4,4,8,8] Output: 2 Example 2: Input: nums = [3,3,7,7,10,11,11] Output: 10    Constraints:  1 <= nums.length <= 105 0 <= nums[i] <= 105  

Topics: Array, Binary Search


# Problem #3: [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water)
> Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.   Example 1:   Input: height = [0,1,0,2,1,0,1,3,2,1,2,1] Output: 6 Explanation: The above elevation map (black section) is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped.  Example 2:  Input: height = [4,2,0,3,2,5] Output: 9    Constraints:  n == height.length 1 <= n <= 2 * 104 0 <= height[i] <= 105  

Topics: Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack