Problem database last updated: June 20, 2025
18 problems · 7 Easy, 8 Medium, 3 Hard · Ranked #98 of 458
7 Easy
39% · avg 23%
8 Medium
44% · avg 59%
3 Hard
17% · avg 18%
Based on 18 reported problems, Barclays interviews are in line with industry averages - 17% Hard vs 18% overall.
Compared to the industry average, Barclays puts unusual emphasis on simulation (11.1% of problems, 2.6x the industry average), depth-first-search (16.7% of problems, 1.8x the industry average), heap-priority-queue (11.1% of problems, 1.8x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (61.1%), string (22.2%), dynamic-programming (22.2%), sorting (16.7%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Furthest Point From Origin You are given a string moves of length n consisting only of characters 'L', 'R', and ''. The string represents your movement on a number line starting from the... | Easy | Very Likely | stringcounting | Solve |
Double Modular Exponentiation You are given a 0-indexed 2D array variables where variables[i] = [ai, bi, ci, mi], and an integer target. | Medium | Very Likely | arraymathsimulation | Solve |
Mark Elements on Array by Performing Queries You are given a 0-indexed array nums of size n consisting of positive integers. | Medium | Very Likely | arrayhash-tablesorting | Solve |
Count Submatrices with Top-Left Element and Sum Less Than k You are given a 0-indexed integer matrix grid and an integer k. | Medium | Very Likely | arraymatrixprefix-sum | Solve |
Lexicographically Smallest Generated String You are given two strings, str1 and str2, of lengths n and m, respectively. A string word of length n + m - 1 is generated by str1 and str2 if for each index 0... | Hard | Very Likely | greedystringstring-matching | 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 |
3Sum Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0. | Medium | Likely | arraytwo-pointerssorting | Solve |
Valid Parentheses Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. | Easy | Likely | stringstack | 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 | Likely | arraydepth-first-searchbreadth-first-search | Solve |
Maximum Employees to Be Invited to a Meeting A company is organizing a meeting and has a list of n employees, waiting to be invited. They have arranged for a large circular table, capable of seating any nu... | Hard | Likely | arraydynamic-programmingdepth-first-search | Solve |
Minimum Number of Refueling Stops A car travels from a starting position to a destination which is target miles east of the starting position. | Hard | Likely | arraydynamic-programminggreedy | Solve |
Isomorphic Strings Given two strings s and t, determine if they are isomorphic. | Easy | Likely | hash-tablestring | Solve |
Climbing Stairs You are climbing a staircase. It takes n steps to reach the top. | Easy | Likely | mathdynamic-programmingmemoization | Solve |
Lexicographical Numbers Given an integer n, return all the numbers in the range [1, n] sorted in lexicographical order. | Medium | Likely | depth-first-searchtrie | Solve |
Palindrome Linked List Given the head of a singly linked list, return true if it is a palindrome or false otherwise. | Easy | Likely | linked-listtwo-pointersstack | Solve |
Permutations Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. | Medium | Likely | arraybacktracking | 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 | Likely | arraytwo-pointerssorting | Solve |
Maximum Subarray Given an integer array nums, find the subarray with the largest sum, and return its sum. | Medium | Likely | arraydivide-and-conquerdynamic-programming | Solve |
Furthest Point From Origin
SolveYou are given a string moves of length n consisting only of characters 'L', 'R', and ''. The string represents your movement on a number line starting from the...
Double Modular Exponentiation
SolveYou are given a 0-indexed 2D array variables where variables[i] = [ai, bi, ci, mi], and an integer target.
Mark Elements on Array by Performing Queries
SolveYou are given a 0-indexed array nums of size n consisting of positive integers.
Count Submatrices with Top-Left Element and Sum Less Than k
SolveYou are given a 0-indexed integer matrix grid and an integer k.
Lexicographically Smallest Generated String
SolveYou are given two strings, str1 and str2, of lengths n and m, respectively. A string word of length n + m - 1 is generated by str1 and str2 if for each index 0...
Two Sum
SolveGiven an array of integers nums and an integer target, return the indices of the two numbers that add up to target.
3Sum
SolveGiven an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.
Valid Parentheses
SolveGiven a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
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.
Maximum Employees to Be Invited to a Meeting
SolveA company is organizing a meeting and has a list of n employees, waiting to be invited. They have arranged for a large circular table, capable of seating any nu...
Minimum Number of Refueling Stops
SolveA car travels from a starting position to a destination which is target miles east of the starting position.
Isomorphic Strings
SolveGiven two strings s and t, determine if they are isomorphic.
Climbing Stairs
SolveYou are climbing a staircase. It takes n steps to reach the top.
Lexicographical Numbers
SolveGiven an integer n, return all the numbers in the range [1, n] sorted in lexicographical order.
Palindrome Linked List
SolveGiven the head of a singly linked list, return true if it is a palindrome or false otherwise.
Permutations
SolveGiven an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.
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...
Maximum Subarray
SolveGiven an integer array nums, find the subarray with the largest sum, and return its sum.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Barclays interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Barclays 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. Barclays 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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Barclays has been reported to ask 18 distinct coding problems. The most common topics are array, string, dynamic-programming. 7 are Easy difficulty, 8 are Medium, and 3 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 18 reported problems, Barclays interviews are in line with industry averages - 17% Hard vs 18% overall. 44% 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 Barclays coding interview with an AI interviewer. Get a scorecard with specific feedback on your problem-solving, code quality, and communication.
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