Problem database last updated: June 20, 2025
12 problems · 1 Easy, 9 Medium, 2 Hard · Ranked #124 of 458
1 Easy
8% · avg 23%
9 Medium
75% · avg 59%
2 Hard
17% · avg 18%
Based on 12 reported problems, Pocket Gems interviews are in line with industry averages - 17% Hard vs 18% overall. The majority (75%) of questions are Medium difficulty, which is typical for companies that want to see solid fundamentals without excessive trick questions.
Compared to the industry average, Pocket Gems puts unusual emphasis on bucket-sort (16.7% of problems, 21.5x the industry average), string-matching (16.7% of problems, 19.1x the industry average), quickselect (16.7% of problems, 15.8x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (58.3%), hash-table (58.3%), sorting (41.7%), string (41.7%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Kth Largest Element in an Array Given an integer array nums and an integer k, return the kth largest element in the array. | Medium | Very Likely | arraydivide-and-conquersorting | Solve |
Shortest Palindrome You are given a string s. You can convert s to a palindrome by adding characters in front of it. | Hard | Very Likely | stringrolling-hashstring-matching | Solve |
Find the Index of the First Occurrence in a String Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. | Easy | Very Likely | two-pointersstringstring-matching | Solve |
Sort Colors Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order... | Medium | Very Likely | arraytwo-pointerssorting | Solve |
Insert Delete GetRandom O(1) Implement the RandomizedSet class: | Medium | Very Likely | arrayhash-tablemath | Solve |
Top K Frequent Elements Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order. | Medium | Very Likely | arrayhash-tabledivide-and-conquer | Solve |
Top K Frequent Words Given an array of strings words and an integer k, return the k most frequent strings. | Medium | Very Likely | arrayhash-tablestring | Solve |
Word Break Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words. | Medium | Very Likely | arrayhash-tablestring | Solve |
Longest Repeating Character Replacement You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform th... | Medium | Very Likely | hash-tablestringsliding-window | Solve |
Clone Graph Given a reference of a node in a connected undirected graph. | Medium | Very Likely | hash-tabledepth-first-searchbreadth-first-search | Solve |
Non-negative Integers without Consecutive Ones Given a positive integer n, return the number of the integers in the range [0, n] whose binary representations do not contain consecutive ones. | Hard | Very Likely | dynamic-programming | Solve |
Find All Duplicates in an Array Given an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears at most twice, return an array of all th... | Medium | Very Likely | arrayhash-tablesorting | Solve |
Kth Largest Element in an Array
SolveGiven an integer array nums and an integer k, return the kth largest element in the array.
Shortest Palindrome
SolveYou are given a string s. You can convert s to a palindrome by adding characters in front of it.
Find the Index of the First Occurrence in a String
SolveGiven two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Sort Colors
SolveGiven an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order...
Insert Delete GetRandom O(1)
SolveImplement the RandomizedSet class:
Top K Frequent Elements
SolveGiven an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.
Top K Frequent Words
SolveGiven an array of strings words and an integer k, return the k most frequent strings.
Word Break
SolveGiven a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.
Longest Repeating Character Replacement
SolveYou are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform th...
Clone Graph
SolveGiven a reference of a node in a connected undirected graph.
Non-negative Integers without Consecutive Ones
SolveGiven a positive integer n, return the number of the integers in the range [0, n] whose binary representations do not contain consecutive ones.
Find All Duplicates in an Array
SolveGiven an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears at most twice, return an array of all th...
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Pocket Gems interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Pocket Gems interviews focus heavily on array, hash-table, sorting problems. If you're short on time, these are the categories to prioritize. The problems on this page are sorted by frequency, so start from the top and work your way down.
Beyond solving problems, practice explaining your approach. Pocket Gems interviewers care about your thought process - how you break down a problem, consider edge cases, and evaluate tradeoffs between solutions. A clean O(n) solution you can explain clearly beats an O(log n) solution you can't articulate.
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Pocket Gems has been reported to ask 12 distinct coding problems. The most common topics are array, hash-table, sorting. 1 are Easy difficulty, 9 are Medium, and 2 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 12 reported problems, Pocket Gems interviews are in line with industry averages - 17% Hard vs 18% overall. 75% of questions are Medium difficulty. Focus on the high-frequency Medium problems first, then work through the Hard ones.
Start with the highest-frequency problems listed on this page. Focus on the core topics: array, hash-table, sorting. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
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