Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Guidewire. 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: Minimum Moves to Spread Stones Over Grid

You are given a 0-indexed 2D integer matrix grid of size 3 * 3, representing the number of stones in each cell. The grid contains exactly 9 stones, and there can be multiple stones in a single cell. In one move, you can move a single stone from its current cell to any other cell if the two cells share a side. Return the minimum number of moves required to place one stone in each cell. Example 1: Input: grid = [[1,1,0],[1,1,1],[1,2,1]] Output: 3 Explanation: One possible sequence of moves to place one stone in each cell is: 1- Move one stone from cell (2,1) to cell (2,2). 2- Move one stone from cell (2,2) to cell (1,2). 3- Move one stone from cell (1,2) to cell (0,2). In total, it takes 3 moves to place one stone in each cell of the grid. It can be shown that 3 is the minimum number of moves required to place one stone in each cell. Example 2: Input: grid = [[1,3,0],[1,0,0],[1,0,3]] Output: 4 Explanation: One possible sequence of moves to place one stone in each cell is: 1- Move one stone from cell (0,1) to cell (0,2). 2- Move one stone from cell (0,1) to cell (1,1). 3- Move one stone from cell (2,2) to cell (1,2). 4- Move one stone from cell (2,2) to cell (2,1). In total, it takes 4 moves to place one stone in each cell of the grid. It can be shown that 4 is the minimum number of moves required to place one stone in each cell. Constraints: grid.length == grid[i].length == 3 0 <= grid[i][j] <= 9 Sum of grid is equal to 9.

Topics: Array, Dynamic Programming, Breadth-First Search, Matrix

Problem #2: Minimum Number of Operations to Sort a Binary Tree by Level

You are given the root of a binary tree with unique values. In one operation, you can choose any two nodes at the same level and swap their values. Return the minimum number of operations needed to make the values at each level sorted in a strictly increasing order. The level of a node is the number of edges along the path between it and the root node. Example 1: Input: root = [1,4,3,7,6,8,5,null,null,null,null,9,null,10] Output: 3 Explanation: - Swap 4 and 3. The 2nd level becomes [3,4]. - Swap 7 and 5. The 3rd level becomes [5,6,8,7]. - Swap 8 and 7. The 3rd level becomes [5,6,7,8]. We used 3 operations so return 3. It can be proven that 3 is the minimum number of operations needed. Example 2: Input: root = [1,3,2,7,6,5,4] Output: 3 Explanation: - Swap 3 and 2. The 2nd level becomes [2,3]. - Swap 7 and 4. The 3rd level becomes [4,6,5,7]. - Swap 6 and 5. The 3rd level becomes [4,5,6,7]. We used 3 operations so return 3. It can be proven that 3 is the minimum number of operations needed. Example 3: Input: root = [1,2,3,4,5,6] Output: 0 Explanation: Each level is already sorted in increasing order so return 0. Constraints: The number of nodes in the tree is in the range [1, 105]. 1 <= Node.val <= 105 All the values of the tree are unique.

Topics: Tree, Breadth-First Search, Binary Tree

Problem #3: Get Watched Videos by Your Friends

There are n people, each person has a unique id between 0 and n-1. Given the arrays watchedVideos and friends, where watchedVideos[i] and friends[i] contain the list of watched videos and the list of friends respectively for the person with id = i. Level 1 of videos are all watched videos by your friends, level 2 of videos are all watched videos by the friends of your friends and so on. In general, the level k of videos are all watched videos by people with the shortest path exactly equal to k with you. Given your id and the level of videos, return the list of videos ordered by their frequencies (increasing). For videos with the same frequency order them alphabetically from least to greatest. Example 1: Input: watchedVideos = [["A","B"],["C"],["B","C"],["D"]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 1 Output: ["B","C"] Explanation: You have id = 0 (green color in the figure) and your friends are (yellow color in the figure): Person with id = 1 -> watchedVideos = ["C"] Person with id = 2 -> watchedVideos = ["B","C"] The frequencies of watchedVideos by your friends are: B -> 1 C -> 2 Example 2: Input: watchedVideos = [["A","B"],["C"],["B","C"],["D"]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 2 Output: ["D"] Explanation: You have id = 0 (green color in the figure) and the only friend of your friends is the person with id = 3 (yellow color in the figure). Constraints: n == watchedVideos.length == friends.length 2 <= n <= 100 1 <= watchedVideos[i].length <= 100 1 <= watchedVideos[i][j].length <= 8 0 <= friends[i].length < n 0 <= friends[i][j] < n 0 <= id < n 1 <= level < n if friends[i] contains j, then friends[j] contains i

Topics: Array, Hash Table, Breadth-First Search, Graph, Sorting

Problem #4: Construct the Longest New String

You are given three integers x, y, and z. You have x strings equal to "AA", y strings equal to "BB", and z strings equal to "AB". You want to choose some (possibly all or none) of these strings and concatenate them in some order to form a new string. This new string must not contain "AAA" or "BBB" as a substring. Return the maximum possible length of the new string. A substring is a contiguous non-empty sequence of characters within a string. Example 1: Input: x = 2, y = 5, z = 1 Output: 12 Explanation: We can concatenate the strings "BB", "AA", "BB", "AA", "BB", and "AB" in that order. Then, our new string is "BBAABBAABBAB". That string has length 12, and we can show that it is impossible to construct a string of longer length. Example 2: Input: x = 3, y = 2, z = 2 Output: 14 Explanation: We can concatenate the strings "AB", "AB", "AA", "BB", "AA", "BB", and "AA" in that order. Then, our new string is "ABABAABBAABBAA". That string has length 14, and we can show that it is impossible to construct a string of longer length. Constraints: 1 <= x, y, z <= 50

Topics: Math, Dynamic Programming, Greedy, Brainteaser