Square software engineer interviews cover algorithms, data structures, system design, and coding problems drawn from real interview rounds.
1. Connect Four
Category: Grid/matrix coding problem
Question Design a ConnectFour class that implements the Connect Four board game. The board is a 6-row by 7-column grid. Two players take turns...
Output: Printed output
2. Page Navigator
Category: Sliding window coding problem
Question Design a PageNavigator class that simulates a paginated view with a sliding window. Given a total number of pages and a window size, the...
Output: Computed result
3. Grid Exits
Category: Grid/matrix coding problem
Question You are given a 2D grid containing open cells (".") and walls ("#"). An exit is any open cell on the border of the grid that is...
Output: Integer
4. Item Price Manager
Category: Algorithm coding problem
Question Design an ItemPriceManager class that tracks the price history of an item over time and supports querying the price at any date and the...
Output: Computed result
5. Pig Latin Translator
Category: Algorithm coding problem
Question Translate a sentence into Pig Latin using the following rules: Rules: 1. If a word begins with a vowel (a, e, i, o, u),...
Output: Computed result
6. Frequency Merge Tree
Category: Tree coding problem
Question Given a string, build a Frequency Merge Tree as follows: 1. Count the frequency of each character in the string. 2. Create a leaf node...
Input: StringOutput: Computed result
7. Obstacle Grid Blocks
Category: Grid/matrix coding problem
Question You are given two integers R and C representing the number of rows and columns in a grid (0-indexed). You are also given a list...
Output: Computed result
8. Soccer Tournament Tracker
Category: String coding problem
Question
Input: Array of stringsOutput: Array
9. Candy Bag Matcher
Category: String coding problem
Question
Input: Array of stringsOutput: Array
1. Binary Search — Find the square root of a number
Problem statement: Given a non-negative integer
x, implement a function that returns the integer part of the square root of x. The square root is defined as the number y such that y * y <= x < (y + 1) * (y + 1). You should implement this using binary search.Function signature:
def my_sqrt(x: int) -> int:
Example 1:
- Input:
x = 8 - Output:
2 - Explanation: The square root of
8is2.828..., so the integer part is2.
Example 2:
- Input:
x = 16 - Output:
4 - Explanation: The square root of
16is4.
Constraints:
0 <= x <= 2 * 10^9
2. [Heap] — Find the k most frequent elements in a dataset
Problem statement: Given a list of integers,
nums, representing transaction IDs, and an integer k, return the k most frequent elements. You need to implement the function topKFrequent(nums: List[int], k: int) -> List[int].Function/class signature:
def topKFrequent(nums: List[int], k: int) -> List[int]:
- Input:
nums = [1,1,1,2,2,3], k = 2 - Output:
[1, 2] - Explanation:
1appears three times, while2appears twice. Therefore, the top two frequent elements are1and2.
- Input:
nums = [1], k = 1 - Output:
[1] - Explanation: Since there’s only one element,
1, it is the only frequent element.
1 <= nums.length <= 10^50 <= nums[i] < 10^41 <= k <= number of unique elements in the array
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