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iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 4/5

Here comes the fourth week of the challenge. Keep grinding. If you need to catch up a bit, you can find challenges of the previous weeks here — Week 1, Week 2, and Week 3

Also, feel free to utilize my Github repo that includes a solution and unit tests for each coding question of the code challenge.

In this article, we’ll discuss the following 7 programming questions from week 4 of the code challenge.

1. Subarray Sum Equals K (Solution) 🥇
2. Bitwise AND of Numbers Range (Solution)
3. LRU Cache (Solution)
4. Jump Game (Solution)
5. Longest Common Subsequence (Solution) 🥉
6. Maximal Square (Solution) 🥈
7. First Unique Number (Solution)

(🥇 🥈 🥉 indicate writer’s selection of high-frequency interview questions.)

Subarray Sum Equals K

🥇 Writer’s selection of the week

Description: Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals k.

Example 
Input:nums = [1, 1, 1], k = 2
Output: 2