Pinterest Coding & Algorithms Interview Questions

Pinterest Coding & Algorithms interview questions focus on algorithmic problem solving, clear code, and pragmatic optimization. Expect an initial recruiter screen and often an online assessment (CodeSignal/LeetCode-style) before a virtual loop of 3–6 interviews that typically include timed coding rounds, follow-ups that probe complexity and edge cases, and domain-focused conversations. What’s distinctive is a balance between pure algorithms and product-aware engineering: interviewers evaluate your data-structure fluency (arrays, strings, trees, graphs, DP), runtime/space trade-offs, test-case thinking, and the ability to explain decisions clearly while iterating on solutions. For effective interview preparation, practice medium-to-hard LeetCode problems under time pressure, rehearse thinking aloud and writing clean, testable code on a shared editor, and simulate follow-ups where you optimize or generalize your solution. Reinforce complexity analysis and common pitfalls (off-by-one, NULL/edge cases, uninitialized state). Finally, prepare concise project stories that show impact and system thinking so you can connect algorithmic choices to real product constraints—this combination of technical rigor and product awareness is how candidates stand out.

66 Questions 1 Company08.02.2026
Showing 20 results
Role
Pinterest logo
Pinterest
Medium
Machine Learning EngineerSenior+ Locked

Solve Expression and Tree-List Problems

This question evaluates competency in string expression generation under a custom left-to-right evaluation rule and in-place binary search tree manipu...

Coding & Algorithms
15
0
108 people solved
Feb 21, 2026
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Pinterest
Hard
Machine Learning Engineer

Insert parentheses to minimize expression value

You are given a string expression of the form A+B, where A and B are non-empty strings of digits (no digit is '0'). You must insert exactly one pair o...

Coding & Algorithms
6
1
115 people solved
Feb 9, 2026
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Pinterest
Medium
Software Engineer Locked

Solve Four Interview Coding Problems

This question set evaluates algorithmic problem-solving skills including graph traversal and itinerary reconstruction, time-sorted search and binary s...

Coding & Algorithms
8
0
60 people solved
Feb 1, 2026
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Pinterest
Medium
Software Engineer Locked

Solve Two Grid Search Problems

This question evaluates proficiency in graph traversal on grids, specifically competencies in identifying connected components and modeling propagatio...

Coding & Algorithms
11
0
76 people solved
Jan 28, 2026
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Pinterest
Medium
Software Engineer Locked

Compute reachable cells for a cleaning robot

This question evaluates understanding of graph traversal, state-space modeling, and scalability when computing reachable cells on a 2D grid under 8-di...

Coding & Algorithms
38
0
270 people solved
Jan 22, 2026
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Pinterest
Medium
Machine Learning Engineer Locked

Generate all hyperparameter combinations

This question evaluates competence in combinatorial enumeration and manipulation of data structures for generating hyperparameter configurations, test...

Coding & Algorithms
12
0
117 people solved
Jan 22, 2026
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Pinterest
Medium
Data Scientist Locked

Implement Jackknife and Random Choice

This question evaluates understanding of statistical resampling (jackknife), probabilistic sampling algorithms including with- and without-replacement...

Coding & Algorithms
8
0
91 people solved
Jan 11, 2026
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Pinterest
Medium
Software Engineer Locked

Implement sparse matrix storage, addition, and multiplication

This question evaluates understanding of sparse matrix representations, algorithmic efficiency for linear algebra operations, and the ability to manip...

Coding & Algorithms
10
0
136 people solved
Jan 6, 2026
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Pinterest
Medium
Data Scientist

Implement and extend My Calendar III

Design and implement a booking system like LeetCode 732 (My Calendar III). Provide a class with methods: book(start, end) using half-open intervals [s...

Coding & Algorithms
6
0
102 people solved
Oct 13, 2025
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Pinterest
Medium
Data Scientist

Find list pair with maximum overlap

You are given N labeled lists of items as a Python dict mapping list_name -> iterable of strings. Example input: {'L1': ['A','B','C'], 'L2': ['A','C',...

Coding & Algorithms
5
0
90 people solved
Oct 13, 2025
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Pinterest
Easy
Data Scientist

Compute average unique pins per user

Task: Average Unique Pins Per User You are given a mapping from user IDs to their lists of pin IDs. Implement a function that computes the mean number...

Coding & Algorithms
12
0
87 people solved
Oct 13, 2025
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Pinterest
Medium
Software Engineer

Implement a min-heap column allocator

You are given an integer k (number of columns) and an array posts of positive integers where posts[i] is the height of the i-th post. All columns star...

Coding & Algorithms
22
0
187 people solved
Sep 6, 2025
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Pinterest
Medium
Software Engineer

Cross-reference logs to flag spam numbers

You are given two data sets: ( 1) a call log containing phone numbers observed in calls and ( 2) a list of user reports where each entry is a phone nu...

Coding & Algorithms
7
0
130 people solved
Sep 6, 2025
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Pinterest
Medium
Software Engineer

Design adjustable ID allocator

Question You manage a fixed global integer ID space [0, 999] (1000 IDs total) and a set of named buckets. Each bucket has a unique name and occupies a...

Coding & Algorithms
14
0
141 people solved
Sep 6, 2025
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Pinterest
Medium
Software Engineer

Decide target via subsequence plus/multiply expression

Question Given a sequence of positive 32-bit integers A and an integer target, determine whether there exists a subsequence of A (preserving order, us...

Coding & Algorithms
12
0
183 people solved
Sep 6, 2025
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Pinterest
Medium
Data Scientist

Calculate 95% Bootstrap Confidence Interval for Order Values

Scenario An e-commerce firm wants a 95% confidence interval for the average order value but only has a single historical sample of order amounts. Ques...

Coding & Algorithms
27
0
45 people solved
Aug 4, 2025
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Pinterest
Medium
Data Scientist

Find available reservation time slots

Problem You are building an API to show which time slots are available for booking at a restaurant. You are given: - The restaurant’s opening hours (p...

Coding & Algorithms
12
0
101 people solved
Aug 2, 2025
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Pinterest
Medium
Software Engineer

Round numeric string values

Question Given a numeric string, implement rounding to the nearest integer (e.g., '3.5' → '4', '100.01' → '100'). Follow-up: round to the last signifi...

Coding & Algorithms
14
0
32 people solved
Jul 29, 2025
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Pinterest
Medium
Software Engineer

Find minimum shuttle transfers

Find minimum shuttle transfers You are given a collection of shuttle loops, each represented by a list of stop IDs that the loop visits in perpetuity....

Coding & Algorithms
9
0
93 people solved
Jul 26, 2025
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Pinterest
Medium
Data Scientist

Implement DelayQueue with Idempotent Task Execution

Scenario Message broker offers DelayQueue where tasks execute at future timestamps, ensuring idempotency on duplicate IDs. Question Implement a delay ...

Coding & Algorithms
29
0
68 people solved
Jul 12, 2025

Frequently Asked Questions

How difficult are Pinterest Coding & Algorithms interview questions for software roles?
Pinterest Coding & Algorithms problems are typically in the medium-to-hard range for software engineering roles and often resemble LeetCode-style algorithmic challenges. Interviewers evaluate algorithmic thinking, correctness, efficiency, and code clarity rather than obscure trivia. Expect questions that require working through edge cases, explaining time and space complexity, and iterating from a brute-force idea to an optimized solution. Difficulty can vary by level; entry-level roles skew easier while senior roles demand algorithmic fluency plus design tradeoffs. Practicing timed problem-solving and clear verbalization of thought process will substantially reduce the perceived difficulty.
What is the interview process at Pinterest and where do Coding & Algorithms questions typically appear?
Pinterest’s technical hiring process normally begins with a recruiter call, followed by one or more technical screens and then an onsite or virtual interview loop. Coding & Algorithms questions commonly appear in the initial technical phone or online screen and again in the onsite loop as dedicated data-structures/algorithms interviews. Domain-specific or system-design interviews may also include algorithmic subproblems. For specialized engineering tracks, coding tasks can appear in take-home assessments or in role-specific rounds. Across stages, interviewers expect clear problem decomposition, correct implementation, and complexity analysis.
How should I structure my preparation timeline for Pinterest Coding & Algorithms interviews?
A focused preparation timeline of six to ten weeks often works well: start with fundamentals, then move to timed practice and mock interviews. Early weeks should reinforce core data structures and algorithm patterns, followed by practicing medium-to-hard problems under time pressure. In the middle of the timeline, incorporate mock interviews with feedback and review common pitfalls you encounter. In the final one to two weeks, prioritize breadth by revisiting weak topics, practicing end-to-end problem explanations, and rehearsing concise complexity analysis. Throughout, balance coding practice with clear verbalization and writing clean, testable code.
Which key subtopics in Coding & Algorithms should I prioritize for Pinterest interviews?
Prioritize core data structures and algorithmic patterns that frequently appear in interviews: arrays and strings, hashing, two-pointers and sliding windows, stacks and queues, trees and binary search trees, graphs with BFS/DFS, dynamic programming, and sorting/searching techniques. Also focus on complexity analysis, tradeoffs between time and space, handling nulls and edge cases, and implementing robust test cases. For performance-sensitive questions, have an intuition for runtime bottlenecks and basic optimizations. Practicing these subtopics in a variety of problem shapes builds the pattern recognition interviewers value.
What standout tips and common pitfalls should I know when preparing for Pinterest Coding & Algorithms interviews?
Standout preparation tips include explicitly clarifying constraints and inputs before coding, narrating your problem-solving steps, and writing correct, well-indented code with simple test cases. Start with a clear brute-force approach, then refine it while explaining tradeoffs in time and space. Common pitfalls are rushing to code without a plan, ignoring edge cases or integer overflows, and failing to justify algorithmic choices. For senior roles, avoid over-optimizing prematurely; instead demonstrate principled tradeoffs. Finally, solicit brief feedback when stuck and use small examples to validate your approach before submitting code.

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