Goldman Sachs, a global leader in financial services, is renowned for its rigorous hiring process, particularly for technology roles. A critical component of these interviews involves tackling coding challenges, often drawing from platforms like LeetCode. Aspiring software engineers, data scientists, and quantitative analysts frequently face a gauntlet of questions designed to assess their proficiency in data structures, algorithms, and problem-solving. Success in these technical rounds hinges on not just knowing the answers, but understanding the underlying concepts and demonstrating clear, efficient coding practices. This article compiles 30 of the most frequently encountered Goldman Sachs LeetCode interview questions, providing actionable advice and example answers to help you navigate your preparation effectively.
What Are Goldman Sachs LeetCode Interview Questions?
Goldman Sachs LeetCode interview questions are algorithmic challenges similar to those found on the LeetCode platform, tailored to evaluate a candidate's core computer science knowledge and coding ability. These questions span various difficulty levels, from easy to hard, and cover fundamental data structures such as arrays, linked lists, trees, graphs, and hash tables, alongside essential algorithms like dynamic programming, greedy algorithms, backtracking, sorting, and searching. The problems are designed to test logical thinking, efficiency (time and space complexity), and the ability to translate conceptual solutions into clean, executable code. Familiarity with these types of problems is crucial for anyone aiming for a technical role at Goldman Sachs.
Why Do Interviewers Ask Goldman Sachs LeetCode Interview Questions?
Interviewers at Goldman Sachs utilize LeetCode-style questions for several key reasons. Firstly, they serve as a standardized method to gauge a candidate's foundational computer science understanding and problem-solving skills under pressure. The ability to break down a complex problem, identify an optimal approach, and implement it correctly reflects a candidate's analytical prowess and coding discipline. Secondly, these questions assess proficiency in efficient algorithm design, critical for building scalable and high-performance financial systems where milliseconds can count. Lastly, it evaluates how candidates communicate their thought process, articulate trade-offs, and handle edge cases—skills vital for collaborative development within a demanding environment. It’s about demonstrating robust technical competency, not just memorizing solutions.
Two Sum
Valid Parentheses
Group Anagrams
Longest Substring Without Repeating Characters
Kth Largest Element in an Array
Trapping Rain Water
Fraction to Recurring Decimal
First Unique Character in a String
Design HashMap
Open the Lock
Maximum Sum Circular Subarray
Search in Rotated Sorted Array
Combination Sum
Jump Game II
Permutations
Minimum Path Sum
Climbing Stairs
Merge Sorted Array
Decode Ways
Validate Binary Search Tree
Pascal’s Triangle
Best Time to Buy and Sell Stock
Copy List with Random Pointer
Linked List Cycle
Next Permutation
Subsets
Gas Station
Unique Frequencies
Pivot Index
All Possible Balanced Parentheses
Preview List
1. How do you find two numbers in an array that sum up to a specific target?
Why you might get asked this:
This easy problem tests your understanding of hash tables for efficient lookups, a common technique in Goldman Sachs LeetCode interview questions. It assesses basic array traversal and data structure usage.
How to answer:
Use a hash map to store numbers encountered and their indices. For each number, check if its complement (target - current_num) exists in the map.
Example answer:
Iterate through the array. For each num, calculate complement = target - num. If complement is in the hash map, return [map[complement], i]. Otherwise, add num and i to the map.
2. How do you determine if a string of parentheses is valid?
Why you might get asked this:
This problem evaluates your ability to use a stack data structure, crucial for handling nested structures and common in Goldman Sachs LeetCode interview questions.
How to answer:
Use a stack. Push opening brackets. On a closing bracket, pop from stack and check for a match. If no match or stack empty, it's invalid. Stack must be empty at the end.
Example answer:
Initialize an empty stack. Map closing brackets to opening ones. Iterate string: push opening, pop and check for matching closing. If mismatch or empty stack on pop, return false. Final stack must be empty.
3. How do you group anagrams together from a list of strings?
Why you might get asked this:
This medium-level problem tests hash map usage with string manipulation, common in Goldman Sachs LeetCode interview questions. It requires understanding of canonical forms.
How to answer:
Create a canonical form for each string (e.g., by sorting its characters). Use this sorted string as a key in a hash map to group original strings.
Example answer:
For each string, sort its characters to form a key (e.g., "eat" -> "aet"). Store original string in a list mapped to this key in a dictionary. Return all dictionary values.
4. How do you find the length of the longest substring without repeating characters?
Why you might get asked this:
This problem assesses your understanding of the sliding window technique, a fundamental pattern in Goldman Sachs LeetCode interview questions for array/string problems.
How to answer:
Use a sliding window (two pointers) and a hash set to track characters within the current window. Expand the window, and if a repeat is found, shrink from the left.
Example answer:
Use left, right pointers and a set. While right < len(s): if s[right] not in set, add it and right++, update max length. Else, remove s[left] and left++.
5. How do you find the Kth largest element in an unsorted array?
Why you might get asked this:
This problem tests sorting algorithms or heap (priority queue) usage, often seen in Goldman Sachs LeetCode interview questions for efficient element retrieval.
How to answer:
Use a min-heap of size K. Iterate through the array; push elements onto the heap. If heap size exceeds K, pop the smallest element. The top of the heap is the Kth largest.
Example answer:
Build a min-heap. For each num in the array, heapq.heappush(heap, num). If len(heap) > k, heapq.heappop(heap). Finally, heap[0] is the Kth largest.
6. How do you calculate the amount of water trapped between bars after a rainfall?
Why you might get asked this:
This hard problem tests advanced two-pointer techniques or stack usage, highlighting efficient solutions often sought in Goldman Sachs LeetCode interview questions.
How to answer:
Use two pointers, left and right, from both ends. Maintain maxleft and maxright. Calculate trapped water by min(maxleft, maxright) - height[current].
Example answer:
Initialize left=0, right=len(height)-1, maxleft=0, maxright=0, water=0. While left < right, if height[left] < height[right], update maxleft and add maxleft - height[left] to water, then left++. Else, update maxright and add maxright - height[right] to water, then right--. Return water.
7. How do you convert a fraction to its recurring decimal representation?
Why you might get asked this:
This problem assesses your handling of edge cases, integer division, and detection of repeating patterns using hash maps, a common test in Goldman Sachs LeetCode interview questions.
How to answer:
Handle sign and integer part. For the fractional part, use a hash map to store remainders and their positions. If a remainder repeats, a cycle is found.
Example answer:
Start with num/den. Append integer part. For remainder, multiply by 10. Store remainder and its index in a map. If remainder repeats, insert () at the stored index.
8. How do you find the first unique character in a string?
Why you might get asked this:
This easy problem checks basic string manipulation and hash table usage for frequency counting, a fundamental skill often assessed in Goldman Sachs LeetCode interview questions.
How to answer:
Use a hash map to store character frequencies. Then, iterate through the string again to find the first character with a frequency of one.
Example answer:
Count character frequencies using a hash map. Iterate through the string; if char_counts[char] is 1, return its index. If no unique character, return -1.
9. How would you design a HashMap from scratch?
Why you might get asked this:
This design problem tests your understanding of hash table internals, collision resolution, and capacity management, essential for lower-level system design in Goldman Sachs LeetCode interview questions.
How to answer:
Implement an array of linked lists (buckets) for collision handling. Define hash function, put, get, remove methods. Consider resizing.
Example answer:
Use an array buckets where each bucket is a list of [key, value] pairs. Implement _hash(key) to get index. put: iterate bucket, update/add. get: iterate bucket, find key. remove: iterate, delete.
10. How do you find the minimum number of turns to open a lock from "0000" to a target combination?
Why you might get asked this:
This medium problem tests Breadth-First Search (BFS) on a graph, where states are lock combinations. BFS is a common pattern in Goldman Sachs LeetCode interview questions for shortest path on unweighted graphs.
How to answer:
Use BFS. Start with "0000". In each step, generate all 8 possible next combinations (spin one wheel up/down). Use a queue and a visited set (including dead ends).
Example answer:
Initialize queue with ("0000", 0). Add "0000" to visited set. If "0000" is a dead end, return -1. Pop state, generate neighbors. If neighbor is target, return turns. Else, enqueue if not visited/dead end.
11. How do you find the maximum sum of a circular subarray?
Why you might get asked this:
This medium problem extends Kadane's algorithm, testing dynamic programming and handling circularity, a good challenge for Goldman Sachs LeetCode interview questions.
How to answer:
Find max subarray sum (Kadane's). Then, find min subarray sum. Max circular sum is totalsum - minsubarray_sum. Compare this with max non-circular sum.
Example answer:
Apply Kadane's algorithm to find maxsofar (normal max subarray sum). Calculate minsofar (min subarray sum). The circular sum is totalsum - minsofar. Return max(maxsofar, circularsum). Handle all negatives.
12. How do you search for a target value in a rotated sorted array?
Why you might get asked this:
This problem assesses modified binary search, requiring adaptation of a fundamental algorithm. It's frequently asked in Goldman Sachs LeetCode interview questions to test logical reasoning.
How to answer:
Perform a binary search, but in each step, determine which half is sorted. Based on the target value, decide whether to search in the sorted or unsorted half.
Example answer:
Use left, right pointers. Calculate mid. If nums[mid] == target, return mid. Else, if nums[left] <= nums[mid] (left half sorted), check if target is in range [nums[left], nums[mid]). Adjust left/right.
13. How do you find all unique combinations of numbers that sum up to a target?
Why you might get asked this:
This medium problem tests backtracking, a recursive technique for exploring all solutions, often appearing in Goldman Sachs LeetCode interview questions for combinatorial problems.
How to answer:
Use a recursive backtracking function. Sort candidates to handle duplicates efficiently. At each step, either include the current number or skip it.
Example answer:
Define backtrack(remain, combo, startindex). Base cases: remain < 0 (invalid), remain == 0 (add combo to results). Recursive step: iterate from startindex, combo.append(num), backtrack(remain - num, combo, i). combo.pop().
14. How do you find the minimum number of jumps to reach the last index of an array?
Why you might get asked this:
This medium problem tests greedy algorithms or dynamic programming, focusing on optimization and efficient traversal—a key aspect of Goldman Sachs LeetCode interview questions.
How to answer:
Use a greedy approach. Maintain currentreach (farthest reachable index with current jumps) and maxreach (farthest reachable index from current position). Increment jumps when i exceeds current_reach.
Example answer:
Initialize jumps=0, currentjumpend=0, farthest=0. Iterate through array: farthest = max(farthest, i + nums[i]). If i == currentjumpend, increment jumps and update currentjumpend = farthest.
15. How do you generate all possible permutations of a list of distinct numbers?
Why you might get asked this:
This problem tests backtracking, a crucial recursive pattern for generating combinations and permutations. It is a common type of Goldman Sachs LeetCode interview question.
How to answer:
Use a recursive backtracking function. At each step, iterate through available numbers, add one to the current permutation, mark it as used, and recurse. Backtrack by removing it.
Example answer:
backtrack(currentpermutation, usedmask): Base case: len(current_permutation) == len(nums). Recursive step: iterate i from 0 to len(nums)-1. If i not used, add nums[i], mark used, backtrack(), then remove nums[i], unmark used.
16. How do you find the minimum path sum in a grid?
Why you might get asked this:
This medium problem involves dynamic programming on a 2D grid, a standard pattern for optimization problems. It frequently appears in Goldman Sachs LeetCode interview questions.
How to answer:
Use dynamic programming. dp[i][j] represents the minimum path sum to reach (i, j). Fill DP table using dp[i][j] = grid[i][j] + min(dp[i-1][j], dp[i][j-1]). Handle base cases.
Example answer:
Create dp table same size as grid. dp[0][0] = grid[0][0]. Fill first row and column. For (i,j), dp[i][j] = grid[i][j] + min(dp[i-1][j], dp[i][j-1]). Return dp[m-1][n-1].
17. How many distinct ways are there to climb to the top of n stairs?
Why you might get asked this:
This easy problem is a classic dynamic programming example, often used as an introduction to the concept. It's a foundational type of Goldman Sachs LeetCode interview question.
How to answer:
This is a Fibonacci sequence variation. dp[i] is the number of ways to reach stair i. dp[i] = dp[i-1] + dp[i-2]. Base cases dp[1]=1, dp[2]=2.
Example answer:
If n <= 2, return n. Create dp array. dp[1]=1, dp[2]=2. Iterate i from 3 to n, dp[i] = dp[i-1] + dp[i-2]. Return dp[n].
18. How do you merge two sorted arrays into one sorted array?
Why you might get asked this:
This easy problem tests array manipulation and two-pointer techniques, focusing on in-place modification and efficiency. It's a common warm-up in Goldman Sachs LeetCode interview questions.
How to answer:
Use a two-pointer approach, starting from the end of both arrays and placing larger elements at the end of the first array (if merging in-place).
Example answer:
Set pointers p1 to end of nums1 valid elements, p2 to end of nums2, p to end of nums1 total length. While p1 >= 0 and p2 >= 0, compare nums1[p1] and nums2[p2], place larger at nums1[p], decrement respective pointers and p. Copy remaining nums2 elements if any.
19. How many ways can a message containing letters from A-Z be decoded?
Why you might get asked this:
This medium problem involves dynamic programming, requiring careful handling of character combinations and edge cases (e.g., '0'). It's a good test for Goldman Sachs LeetCode interview questions.
How to answer:
Use DP. dp[i] is the number of ways to decode substring s[0...i-1]. Consider single-digit and two-digit decodings, handling '0' carefully.
Example answer:
dp[0] = 1, dp[1] = 1 if s[0] != '0'. Iterate i from 2 to n:dp[i] = dp[i-1] if s[i-1] is valid (1-9).dp[i] += dp[i-2] if s[i-2:i] is valid (10-26).
Return dp[n].
20. How do you validate if a given binary tree is a valid Binary Search Tree (BST)?
Why you might get asked this:
This medium problem checks your understanding of tree traversals (DFS, in-order) and BST properties, a frequent topic in Goldman Sachs LeetCode interview questions.
How to answer:
Perform an in-order traversal. For a valid BST, the elements visited in in-order traversal should be strictly increasing. Keep track of the prev visited node's value.
Example answer:
isValidBST(root, minval, maxval): Base case root is None, return true. Recursive check: root.val > minval and root.val < maxval, then recursively check left child with (minval, root.val) and right child with (root.val, maxval).
21. How do you generate Pascal’s Triangle up to a given number of rows?
Why you might get asked this:
This easy array problem tests iterative pattern generation and basic list manipulation, serving as a good warm-up or quick check in Goldman Sachs LeetCode interview questions.
How to answer:
Generate row by row. Each number is the sum of the two numbers directly above it in the previous row. Start and end of each row are always 1.
Example answer:
Initialize result = []. For i from 0 to numRows-1: create currentrow = [1]*(i+1). If i > 1, iterate j from 1 to i-1, currentrow[j] = result[i-1][j-1] + result[i-1][j]. Add current_row to result.
22. What is the maximum profit you can achieve by buying and selling a stock?
Why you might get asked this:
This easy problem assesses basic array iteration and finding minimums/maximums, demonstrating efficient one-pass solutions often preferred in Goldman Sachs LeetCode interview questions.
How to answer:
Iterate through prices, keeping track of the minimum price encountered so far. At each step, calculate the potential profit and update the maximum profit.
Example answer:
Initialize minprice = infinity and maxprofit = 0. Iterate through price in prices: minprice = min(minprice, price). maxprofit = max(maxprofit, price - minprice). Return maxprofit.
23. How do you copy a linked list with random pointers?
Why you might get asked this:
This medium linked list problem tests complex pointer manipulation and hash map usage to handle random connections efficiently. It's a common challenge in Goldman Sachs LeetCode interview questions.
How to answer:
Use a hash map to store originalnode -> copiednode mappings. Iterate once to create new nodes and populate next pointers, then iterate again to populate random pointers using the map.
Example answer:
Create a map oldtonew for node mapping. Iterate original list: oldtonew[node] = Node(node.val). Iterate again: oldtonew[node].next = oldtonew[node.next], oldtonew[node].random = oldtonew[node.random]. Return oldtonew[head].
24. How do you detect if a linked list has a cycle?
Why you might get asked this:
This easy linked list problem tests the fast and slow pointer technique, a crucial pattern for list manipulation and a common Goldman Sachs LeetCode interview question.
How to answer:
Use two pointers, slow and fast. slow moves one step, fast moves two. If they meet, there's a cycle. If fast or fast.next becomes None, no cycle.
Example answer:
Initialize slow = head, fast = head. While fast and fast.next: slow = slow.next, fast = fast.next.next. If slow == fast, return True. Return False.
25. How do you find the next lexicographically greater permutation of numbers?
Why you might get asked this:
This medium array problem tests understanding of permutations and in-place array manipulation, requiring careful pointer logic. It's a classic Goldman Sachs LeetCode interview question.
How to answer:
Find the first decreasing element from right. Find smallest element to its right that is greater. Swap them. Reverse the subarray to the right of the swap point.
Example answer:
Find i such that nums[i] < nums[i+1] (from right). If no such i, reverse whole array. Find j such that nums[j] > nums[i] (from right). Swap nums[i] and nums[j]. Reverse subarray from i+1 to end.
26. How do you generate all possible subsets of a set of distinct integers?
Why you might get asked this:
This medium problem tests backtracking or bit manipulation for combinatorial generation, a frequently asked type in Goldman Sachs LeetCode interview questions.
How to answer:
Use backtracking: for each element, decide to include it or not. Or, use bit manipulation: each bit in a counter corresponds to including/excluding an element.
Example answer:
backtrack(index, currentsubset): Base case: add currentsubset to results. Recursive step: currentsubset.append(nums[index]), backtrack(index + 1, currentsubset). currentsubset.pop(). backtrack(index + 1, currentsubset).
27. How do you find the starting gas station index to complete a circular tour?
Why you might get asked this:
This medium problem tests greedy algorithms, focusing on maintaining a balance and identifying a valid starting point efficiently. It is a common Goldman Sachs LeetCode interview question.
How to answer:
Iterate, track currenttank and totaltank. If currenttank drops below zero, reset currenttank and update startnode. If totaltank is negative at end, no solution.
Example answer:
Initialize totalgas = 0, currentgas = 0, startstation = 0. Iterate i from 0 to n-1: totalgas += gas[i] - cost[i], currentgas += gas[i] - cost[i]. If currentgas < 0, currentgas = 0, startstation = i + 1. If totalgas < 0, return -1. Else, return startstation.
28. How do you find unique frequencies of elements in an array?
Why you might get asked this:
This medium problem assesses hash map usage for frequency counting and then a hash set to check for unique frequencies. It tests two-step data structure application.
How to answer:
First, count frequencies of each number using a hash map. Second, store these frequencies in a hash set. If any frequency is already in the set, they are not unique.
Example answer:
Use a collections.Counter (or hash map) to get element frequencies. Then, create a set of these frequencies. If len(setoffrequencies) == len(dictoffrequencies), return True, else False.
29. How do you find the pivot index in an array where sum of left and right halves are equal?
Why you might get asked this:
This easy array problem introduces prefix sums, an optimization technique. It's often used in Goldman Sachs LeetCode interview questions to check for efficient sum calculation.
How to answer:
Calculate the total sum of the array. Iterate through the array, maintaining a leftsum. The rightsum is totalsum - leftsum - currentnum. Return index if leftsum == right_sum.
Example answer:
Calculate totalsum of array. Initialize leftsum = 0. Iterate i through nums: rightsum = totalsum - leftsum - nums[i]. If leftsum == rightsum, return i. Else, leftsum += nums[i]. Return -1.
30. How do you generate all possible balanced parentheses for n pairs?
Why you might get asked this:
This medium problem is a classic backtracking challenge, involving constraints on building valid structures. It’s frequently asked in Goldman Sachs LeetCode interview questions.
How to answer:
Use backtracking. Maintain opencount and closecount. Only add '(' if opencount < n. Only add ')' if closecount < opencount. Base case when opencount == n and close_count == n.
Example answer:
generate(currentstring, openc, closec): If len(currentstring) == 2n, add to result. If openc < n, generate(currentstring + "(", openc + 1, closec). If closec < openc, generate(currentstring + ")", openc, close_c + 1).
Other Tips to Prepare for a Goldman Sachs LeetCode Interview
Mastering Goldman Sachs LeetCode interview questions requires more than just memorizing solutions; it demands a deep understanding of core computer science principles and robust problem-solving skills. As software engineer John Sonmez once said, "The only way to do great work is to love what you do. If you haven't found it yet, keep looking. Don't settle." This applies to your preparation as well – approach it with genuine curiosity.
Beyond practicing individual problems, focus on recognizing common algorithmic patterns such as dynamic programming, greedy algorithms, backtracking, and various graph traversals. Understand the time and space complexity implications of your solutions. Crucially, practice explaining your thought process clearly and concisely, as communication is key in Goldman Sachs technical interviews. Mock interviews are invaluable for refining this skill under pressure. Consider using tools like Verve AI Interview Copilot to simulate real interview scenarios and receive instant feedback on your approach and code. Verve AI Interview Copilot can help you articulate your solutions better and identify areas for improvement. Leverage its features to refine your explanations and ensure you cover all edge cases. For further practice and detailed insights, explore resources like https://vervecopilot.com. As Benjamin Franklin advised, "By failing to prepare, you are preparing to fail." Take advantage of every tool available, including Verve AI Interview Copilot, to maximize your readiness for Goldman Sachs coding challenges.
Frequently Asked Questions
Q1: How much LeetCode should I do for Goldman Sachs?
A1: Aim for at least 150-200 medium to hard problems, focusing on common patterns relevant to their interview questions.
Q2: Are Goldman Sachs LeetCode questions difficult?
A2: They range from easy to hard, with a strong emphasis on medium difficulty problems that test core DSA and algorithmic thinking.
Q3: What data structures are most important for Goldman Sachs LeetCode interviews?
A3: Arrays, strings, hash tables, linked lists, trees (especially BSTs), and graphs are critically important.
Q4: Should I memorize solutions to Goldman Sachs LeetCode interview questions?
A4: No, focus on understanding the underlying algorithms and problem-solving techniques rather than memorizing specific answers.
Q5: Is it okay to use Python for Goldman Sachs LeetCode interviews?
A5: Yes, most modern companies, including Goldman Sachs, allow popular languages like Python, Java, and C++.
Q6: How long does a Goldman Sachs technical interview typically last?
A6: Technical interviews usually last 45-60 minutes, with most of that time dedicated to solving 1-2 LeetCode-style problems.
