Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Box. 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: Top K Frequent Words

Given an array of strings words and an integer k, return the k most frequent strings. Return the answer sorted by the frequency from highest to lowest. Sort the words with the same frequency by their lexicographical order. Example 1: Input: words = ["i","love","leetcode","i","love","coding"], k = 2 Output: ["i","love"] Explanation: "i" and "love" are the two most frequent words. Note that "i" comes before "love" due to a lower alphabetical order. Example 2: Input: words = ["the","day","is","sunny","the","the","the","sunny","is","is"], k = 4 Output: ["the","is","sunny","day"] Explanation: "the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively. Constraints: 1 <= words.length <= 500 1 <= words[i].length <= 10 words[i] consists of lowercase English letters. k is in the range [1, The number of unique words[i]] Follow-up: Could you solve it in O(n log(k)) time and O(n) extra space?

Topics: Array, Hash Table, String, Trie, Sorting, Heap (Priority Queue), Bucket Sort, Counting

Problem #2: Number of 1 Bits

Given a positive integer n, write a function that returns the number of set bits in its binary representation (also known as the Hamming weight). Example 1: Input: n = 11 Output: 3 Explanation: The input binary string 1011 has a total of three set bits. Example 2: Input: n = 128 Output: 1 Explanation: The input binary string 10000000 has a total of one set bit. Example 3: Input: n = 2147483645 Output: 30 Explanation: The input binary string 1111111111111111111111111111101 has a total of thirty set bits. Constraints: 1 <= n <= 231 - 1 Follow up: If this function is called many times, how would you optimize it?

Topics: Divide and Conquer, Bit Manipulation