Problem database last updated: June 20, 2025
63 problems · 8 Easy, 48 Medium, 7 Hard · Ranked #39 of 458
8 Easy
13% · avg 23%
48 Medium
76% · avg 59%
7 Hard
11% · avg 18%
Based on 63 reported problems, ByteDance interviews are in line with industry averages - 11% Hard vs 18% overall. The majority (76%) 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, ByteDance puts unusual emphasis on merge-sort (3.2% of problems, 4.3x the industry average), quickselect (3.2% of problems, 3x the industry average), topological-sort (3.2% of problems, 2.7x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (52.4%), string (25.4%), dynamic-programming (23.8%), hash-table (20.6%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
LRU Cache Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. | Medium | Very Likely | hash-tablelinked-listdesign | Solve |
Smallest Subsequence of Distinct Characters Given a string s, return the lexicographically smallest subsequence of s that contains all the distinct characters of s exactly once. | Medium | Very Likely | stringstackgreedy | Solve |
First Day Where You Have Been in All the Rooms There are n rooms you need to visit, labeled from 0 to n - 1. Each day is labeled, starting from 0. You will go in and visit one room a day. | Medium | Very Likely | arraydynamic-programming | Solve |
Remove Duplicate Letters Given a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical or... | Medium | Very Likely | stringstackgreedy | Solve |
Number of Islands Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands. | Medium | Very Likely | arraydepth-first-searchbreadth-first-search | Solve |
Course Schedule There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b... | Medium | Very Likely | depth-first-searchbreadth-first-searchgraph | Solve |
Longest Substring Without Repeating Characters Given a string s, find the length of the longest substring without duplicate characters. | Medium | Likely | hash-tablestringsliding-window | Solve |
Combination Sum Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum... | Medium | Likely | arraybacktracking | Solve |
Kth Largest Element in an Array Given an integer array nums and an integer k, return the kth largest element in the array. | Medium | Likely | arraydivide-and-conquersorting | Solve |
Basic Calculator II Given a string s which represents an expression, evaluate this expression and return its value. | Medium | Likely | mathstringstack | Solve |
Regular Expression Matching Given an input string s and a pattern p, implement regular expression matching with support for '.' and '' where: | Hard | Likely | stringdynamic-programmingrecursion | Solve |
Longest Consecutive Sequence Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence. | Medium | Likely | arrayhash-tableunion-find | Solve |
House Robber You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob... | Medium | Likely | arraydynamic-programming | Solve |
Trapping Rain Water Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. | Hard | Likely | arraytwo-pointersdynamic-programming | Solve |
Search in Rotated Sorted Array There is an integer array nums sorted in ascending order (with distinct values). | Medium | Likely | arraybinary-search | Solve |
House Robber II You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in... | Medium | Likely | arraydynamic-programming | Solve |
Merge Intervals Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove... | Medium | Likely | arraysorting | Solve |
Two Sum Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target. | Easy | Likely | arrayhash-map | Solve |
Insert Delete GetRandom O(1) Implement the RandomizedSet class: | Medium | Likely | arrayhash-tablemath | Solve |
Maximal Square Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area. | Medium | Likely | arraydynamic-programmingmatrix | Solve |
Longest Common Subsequence Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0. | Medium | Likely | stringdynamic-programming | Solve |
Add Two Numbers You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a sing... | Medium | Likely | linked-listmathrecursion | Solve |
Basic Calculator Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation. | Hard | Likely | mathstringstack | Solve |
Rotting Oranges You are given an m x n grid where each cell can have one of three values: | Medium | Likely | arraybreadth-first-searchmatrix | Solve |
Sum Game Alice and Bob take turns playing a game, with Alice starting first. | Medium | Likely | mathstringgreedy | Solve |
Number of Good Leaf Nodes Pairs You are given the root of a binary tree and an integer distance. A pair of two different leaf nodes of a binary tree is said to be good if the length of the sho... | Medium | Likely | treedepth-first-searchbinary-tree | Solve |
Sort List Given the head of a linked list, return the list after sorting it in ascending order. | Medium | Likely | linked-listtwo-pointersdivide-and-conquer | Solve |
Delete Operation for Two Strings Given two strings word1 and word2, return the minimum number of steps required to make word1 and word2 the same. | Medium | Likely | stringdynamic-programming | 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 | Likely | arrayhash-tabledivide-and-conquer | Solve |
Subarray Sum Equals K Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k. | Medium | Likely | arrayhash-tableprefix-sum | Solve |
Combination Sum II Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to... | Medium | Likely | arraybacktracking | Solve |
Best Time to Buy and Sell Stock You are given an array prices where prices[i] is the price of a given stock on the ith day. | Easy | Likely | arraydynamic-programming | Solve |
Remove Zero Sum Consecutive Nodes from Linked List Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences. | Medium | Sometimes | hash-tablelinked-list | Solve |
Climbing Stairs You are climbing a staircase. It takes n steps to reach the top. | Easy | Sometimes | mathdynamic-programmingmemoization | Solve |
Longest Palindromic Substring Given a string s, return the longest palindromic substring in s. | Medium | Sometimes | two-pointersstringdynamic-programming | Solve |
Merge Sorted Array You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and num... | Easy | Sometimes | arraytwo-pointerssorting | Solve |
Container With Most Water You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]). | Medium | Sometimes | arraytwo-pointersgreedy | Solve |
Reverse Linked List Given the head of a singly linked list, reverse the list, and return the reversed list. | Easy | Sometimes | linked-listrecursion | Solve |
Next Permutation A permutation of an array of integers is an arrangement of its members into a sequence or linear order. | Medium | Sometimes | arraytwo-pointers | Solve |
Peak Index in a Mountain Array You are given an integer mountain array arr of length n where the values increase to a peak element and then decrease. | Medium | Sometimes | arraybinary-search | Solve |
Unique Paths There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner... | Medium | Sometimes | mathdynamic-programmingcombinatorics | Solve |
Pow(x, n) Implement pow(x, n), which calculates x raised to the power n (i.e., xn). | Medium | Sometimes | mathrecursion | Solve |
Decode String Given an encoded string, return its decoded string. | Medium | Sometimes | stringstackrecursion | Solve |
Subsets Given an integer array nums of unique elements, return all possible subsets (the power set). | Medium | Sometimes | arraybacktrackingbit-manipulation | Solve |
Merge k Sorted Lists You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. | Hard | Sometimes | linked-listdivide-and-conquerheap-priority-queue | Solve |
Binary Tree Zigzag Level Order Traversal Given the root of a binary tree, return the zigzag level order traversal of its nodes' values. (i.e., from left to right, then right to left for the next level... | Medium | Sometimes | treebreadth-first-searchbinary-tree | Solve |
Minimum Window Substring Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is inc... | Hard | Sometimes | hash-tablestringsliding-window | Solve |
Course Schedule II There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b... | Medium | Sometimes | depth-first-searchbreadth-first-searchgraph | Solve |
Compare Version Numbers Given two version strings, version1 and version2, compare them. A version string consists of revisions separated by dots '.'. The value of the revision is its i... | Medium | Sometimes | two-pointersstring | Solve |
Design Memory Allocator You are given an integer n representing the size of a 0-indexed memory array. All memory units are initially free. | Medium | Sometimes | arrayhash-tabledesign | Solve |
Search a 2D Matrix II Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties: | Medium | Sometimes | arraybinary-searchdivide-and-conquer | Solve |
Add to Array-Form of Integer The array-form of an integer num is an array representing its digits in left to right order. | Easy | Sometimes | arraymath | Solve |
Open the Lock You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'. The wheels can rotate freely... | Medium | Sometimes | arrayhash-tablestring | Solve |
Trapping Rain Water II Given an m x n integer matrix heightMap representing the height of each unit cell in a 2D elevation map, return the volume of water it can trap after raining. | Hard | Sometimes | arraybreadth-first-searchheap-priority-queue | 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 | Sometimes | hash-tablestringsliding-window | Solve |
Sum of Distances in Tree There is an undirected connected tree with n nodes labeled from 0 to n - 1 and n - 1 edges. | Hard | Sometimes | dynamic-programmingtreedepth-first-search | Solve |
Minimum Area Rectangle You are given an array of points in the X-Y plane points where points[i] = [xi, yi]. | Medium | Sometimes | arrayhash-tablemath | Solve |
H-Index Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper, return the researcher's h-index. | Medium | Sometimes | arraysortingcounting-sort | Solve |
Find All Good Indices You are given a 0-indexed integer array nums of size n and a positive integer k. | Medium | Sometimes | arraydynamic-programmingprefix-sum | Solve |
Degree of an Array Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements. | Easy | Sometimes | arrayhash-table | Solve |
Count Binary Substrings Given a binary string s, return the number of non-empty substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in these substrings... | Easy | Sometimes | two-pointersstring | Solve |
Maximum Value at a Given Index in a Bounded Array You are given three positive integers: n, index, and maxSum. You want to construct an array nums (0-indexed) that satisfies the following conditions: | Medium | Sometimes | mathbinary-searchgreedy | Solve |
Partition to K Equal Sum Subsets Given an integer array nums and an integer k, return true if it is possible to divide this array into k non-empty subsets whose sums are all equal. | Medium | Sometimes | arraydynamic-programmingbacktracking | Solve |
LRU Cache
SolveDesign a data structure that follows the constraints of a Least Recently Used (LRU) cache.
Smallest Subsequence of Distinct Characters
SolveGiven a string s, return the lexicographically smallest subsequence of s that contains all the distinct characters of s exactly once.
First Day Where You Have Been in All the Rooms
SolveThere are n rooms you need to visit, labeled from 0 to n - 1. Each day is labeled, starting from 0. You will go in and visit one room a day.
Remove Duplicate Letters
SolveGiven a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical or...
Number of Islands
SolveGiven an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.
Course Schedule
SolveThere are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...
Longest Substring Without Repeating Characters
SolveGiven a string s, find the length of the longest substring without duplicate characters.
Combination Sum
SolveGiven an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum...
Kth Largest Element in an Array
SolveGiven an integer array nums and an integer k, return the kth largest element in the array.
Basic Calculator II
SolveGiven a string s which represents an expression, evaluate this expression and return its value.
Regular Expression Matching
SolveGiven an input string s and a pattern p, implement regular expression matching with support for '.' and '' where:
Longest Consecutive Sequence
SolveGiven an unsorted array of integers nums, return the length of the longest consecutive elements sequence.
House Robber
SolveYou are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob...
Trapping Rain Water
SolveGiven n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.
Search in Rotated Sorted Array
SolveThere is an integer array nums sorted in ascending order (with distinct values).
House Robber II
SolveYou are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in...
Merge Intervals
SolveGiven an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove...
Two Sum
SolveGiven an array of integers nums and an integer target, return the indices of the two numbers that add up to target.
Maximal Square
SolveGiven an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.
Longest Common Subsequence
SolveGiven two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.
Add Two Numbers
SolveYou are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a sing...
Basic Calculator
SolveGiven a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation.
Rotting Oranges
SolveYou are given an m x n grid where each cell can have one of three values:
Sum Game
SolveAlice and Bob take turns playing a game, with Alice starting first.
Number of Good Leaf Nodes Pairs
SolveYou are given the root of a binary tree and an integer distance. A pair of two different leaf nodes of a binary tree is said to be good if the length of the sho...
Sort List
SolveGiven the head of a linked list, return the list after sorting it in ascending order.
Delete Operation for Two Strings
SolveGiven two strings word1 and word2, return the minimum number of steps required to make word1 and word2 the same.
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.
Subarray Sum Equals K
SolveGiven an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.
Combination Sum II
SolveGiven a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to...
Best Time to Buy and Sell Stock
SolveYou are given an array prices where prices[i] is the price of a given stock on the ith day.
Remove Zero Sum Consecutive Nodes from Linked List
SolveGiven the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences.
Climbing Stairs
SolveYou are climbing a staircase. It takes n steps to reach the top.
Longest Palindromic Substring
SolveGiven a string s, return the longest palindromic substring in s.
Merge Sorted Array
SolveYou are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and num...
Container With Most Water
SolveYou are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).
Reverse Linked List
SolveGiven the head of a singly linked list, reverse the list, and return the reversed list.
Next Permutation
SolveA permutation of an array of integers is an arrangement of its members into a sequence or linear order.
Peak Index in a Mountain Array
SolveYou are given an integer mountain array arr of length n where the values increase to a peak element and then decrease.
Unique Paths
SolveThere is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner...
Pow(x, n)
SolveImplement pow(x, n), which calculates x raised to the power n (i.e., xn).
Decode String
SolveGiven an encoded string, return its decoded string.
Subsets
SolveGiven an integer array nums of unique elements, return all possible subsets (the power set).
Merge k Sorted Lists
SolveYou are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
Binary Tree Zigzag Level Order Traversal
SolveGiven the root of a binary tree, return the zigzag level order traversal of its nodes' values. (i.e., from left to right, then right to left for the next level...
Minimum Window Substring
SolveGiven two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is inc...
Course Schedule II
SolveThere are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...
Compare Version Numbers
SolveGiven two version strings, version1 and version2, compare them. A version string consists of revisions separated by dots '.'. The value of the revision is its i...
Design Memory Allocator
SolveYou are given an integer n representing the size of a 0-indexed memory array. All memory units are initially free.
Search a 2D Matrix II
SolveWrite an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:
Add to Array-Form of Integer
SolveThe array-form of an integer num is an array representing its digits in left to right order.
Open the Lock
SolveYou have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'. The wheels can rotate freely...
Trapping Rain Water II
SolveGiven an m x n integer matrix heightMap representing the height of each unit cell in a 2D elevation map, return the volume of water it can trap after raining.
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...
Sum of Distances in Tree
SolveThere is an undirected connected tree with n nodes labeled from 0 to n - 1 and n - 1 edges.
Minimum Area Rectangle
SolveYou are given an array of points in the X-Y plane points where points[i] = [xi, yi].
H-Index
SolveGiven an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper, return the researcher's h-index.
Find All Good Indices
SolveYou are given a 0-indexed integer array nums of size n and a positive integer k.
Degree of an Array
SolveGiven a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.
Count Binary Substrings
SolveGiven a binary string s, return the number of non-empty substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in these substrings...
Maximum Value at a Given Index in a Bounded Array
SolveYou are given three positive integers: n, index, and maxSum. You want to construct an array nums (0-indexed) that satisfies the following conditions:
Partition to K Equal Sum Subsets
SolveGiven an integer array nums and an integer k, return true if it is possible to divide this array into k non-empty subsets whose sums are all equal.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent ByteDance interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
ByteDance interviews focus heavily on array, string, dynamic-programming 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. ByteDance 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.
Looking for more companies? Browse all 458 companies in our directory, or sharpen your fundamentals with our free data structure visualizers and AI-powered DSA tutor.
ByteDance has been reported to ask 63 distinct coding problems. The most common topics are array, string, dynamic-programming. 8 are Easy difficulty, 48 are Medium, and 7 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 63 reported problems, ByteDance interviews are in line with industry averages - 11% Hard vs 18% overall. 76% 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, string, dynamic-programming. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
Simulate a real ByteDance coding interview with an AI interviewer. Get a scorecard with specific feedback on your problem-solving, code quality, and communication.
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