Problem database last updated: June 20, 2025
20 problems · 4 Easy, 11 Medium, 5 Hard · Ranked #93 of 458
4 Easy
20% · avg 23%
11 Medium
55% · avg 59%
5 Hard
25% · avg 18%
Based on 20 reported problems, Two Sigma interviews are slightly harder than average - 25% Hard vs 18% across all companies. The majority (55%) 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, Two Sigma puts unusual emphasis on trie (10% of problems, 3.8x the industry average), simulation (15% of problems, 3.5x the industry average), graph (10% of problems, 3.4x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (65%), dynamic-programming (35%), binary-search (25%), string (25%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Minimum Operations to Reduce an Integer to 0 You are given a positive integer n, you can do the following operation any number of times: | Medium | Very Likely | dynamic-programminggreedybit-manipulation | Solve |
Number of Provinces There are n cities. Some of them are connected, while some are not. If city a is connected directly with city b, and city b is connected directly with city c, t... | Medium | Very Likely | depth-first-searchbreadth-first-searchunion-find | Solve |
Random Pick with Weight You are given a 0-indexed array of positive integers w where w[i] describes the weight of the ith index. | Medium | Very Likely | arraymathbinary-search | Solve |
Maximum Subarray Sum with One Deletion Given an array of integers, return the maximum sum for a non-empty subarray (contiguous elements) with at most one element deletion. In other words, you want to... | Medium | Very Likely | arraydynamic-programming | Solve |
Maximum Sum Circular Subarray Given a circular integer array nums of length n, return the maximum possible sum of a non-empty subarray of nums. | Medium | Very Likely | arraydivide-and-conquerdynamic-programming | Solve |
Longest String Chain You are given an array of words where each word consists of lowercase English letters. | Medium | Very Likely | arrayhash-tabletwo-pointers | Solve |
Game of Life According to Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway... | Medium | Very Likely | arraymatrixsimulation | Solve |
Power of Four Given an integer n, return true if it is a power of four. Otherwise, return false. | Easy | Very Likely | mathbit-manipulationrecursion | Solve |
Wildcard Matching Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '' where: | Hard | Very Likely | stringdynamic-programminggreedy | Solve |
Multiply Strings Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string. | Medium | Very Likely | mathstringsimulation | Solve |
Intersection of Two Arrays Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any... | Easy | Very Likely | arrayhash-tabletwo-pointers | Solve |
Word Search II Given an m x n board of characters and a list of strings words, return all words on the board. | Hard | Very Likely | arraystringbacktracking | Solve |
Parallel Courses III You are given an integer n, which indicates that there are n courses labeled from 1 to n. You are also given a 2D integer array relations where relations[j] = [... | Hard | Likely | arraydynamic-programminggraph | Solve |
Merge k Sorted Lists You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. | Hard | Likely | linked-listdivide-and-conquerheap-priority-queue | Solve |
Minimum Space Wasted From Packaging You have n packages that you are trying to place in boxes, one package in each box. There are m suppliers that each produce boxes of different sizes (with infin... | Hard | Likely | arraybinary-searchsorting | Solve |
Design HashMap Design a HashMap without using any built-in hash table libraries. | Easy | Likely | arrayhash-tablelinked-list | 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 | Likely | arrayhash-tabledesign | Solve |
Sum of Square Numbers Given a non-negative integer c, decide whether there're two integers a and b such that a2 + b2 = c. | Medium | Likely | mathtwo-pointersbinary-search | Solve |
Search Suggestions System You are given an array of strings products and a string searchWord. | Medium | Likely | arraystringbinary-search | 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 |
Minimum Operations to Reduce an Integer to 0
SolveYou are given a positive integer n, you can do the following operation any number of times:
Number of Provinces
SolveThere are n cities. Some of them are connected, while some are not. If city a is connected directly with city b, and city b is connected directly with city c, t...
Random Pick with Weight
SolveYou are given a 0-indexed array of positive integers w where w[i] describes the weight of the ith index.
Maximum Subarray Sum with One Deletion
SolveGiven an array of integers, return the maximum sum for a non-empty subarray (contiguous elements) with at most one element deletion. In other words, you want to...
Maximum Sum Circular Subarray
SolveGiven a circular integer array nums of length n, return the maximum possible sum of a non-empty subarray of nums.
Longest String Chain
SolveYou are given an array of words where each word consists of lowercase English letters.
Game of Life
SolveAccording to Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway...
Power of Four
SolveGiven an integer n, return true if it is a power of four. Otherwise, return false.
Wildcard Matching
SolveGiven an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '' where:
Multiply Strings
SolveGiven two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
Intersection of Two Arrays
SolveGiven two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any...
Word Search II
SolveGiven an m x n board of characters and a list of strings words, return all words on the board.
Parallel Courses III
SolveYou are given an integer n, which indicates that there are n courses labeled from 1 to n. You are also given a 2D integer array relations where relations[j] = [...
Merge k Sorted Lists
SolveYou are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
Minimum Space Wasted From Packaging
SolveYou have n packages that you are trying to place in boxes, one package in each box. There are m suppliers that each produce boxes of different sizes (with infin...
Design HashMap
SolveDesign a HashMap without using any built-in hash table libraries.
Design Memory Allocator
SolveYou are given an integer n representing the size of a 0-indexed memory array. All memory units are initially free.
Sum of Square Numbers
SolveGiven a non-negative integer c, decide whether there're two integers a and b such that a2 + b2 = c.
Search Suggestions System
SolveYou are given an array of strings products and a string searchWord.
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.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Two Sigma interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Two Sigma interviews focus heavily on array, dynamic-programming, binary-search 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. Two Sigma 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.
Two Sigma has been reported to ask 20 distinct coding problems. The most common topics are array, dynamic-programming, binary-search. 4 are Easy difficulty, 11 are Medium, and 5 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 20 reported problems, Two Sigma interviews are slightly harder than average - 25% Hard vs 18% across all companies. 55% 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, dynamic-programming, binary-search. 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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