Pinterest Interview Guide

The count-and-say sequence is generated iteratively. Given a starting number, compute the next number in the sequence by describing the previous one.

You're given a list of flight tickets, each representing a departure and arrival airport. Reconstruct the itinerary by visiting all the airports in the lexicographically smallest order, starting from "JFK".

You are given a list of transactions between people. Determine the minimum number of transactions needed to settle all debts, such that everyone owes or is owed exactly zero.

Find the shortest path from the top-left to the bottom-right corner of a grid. You can eliminate a limited number of obstacles along the way.

Find the number of subarrays in a given array whose "score" (defined as the product of the subarray's length and sum) is less than a target value k. Efficiently count these subarrays, avoiding brute force.

You're given a list of jobs with start times, end times, and profits. Find the maximum profit you can obtain by scheduling a subset of jobs that don't overlap.

Imagine you're planning a trip using a network of bus routes. Given a set of routes and start/end locations, find the fewest number of buses you must take to reach your destination.

Given a string of digits, find all valid ways to insert '+', '-', or '*' operators to achieve a target number. You need to explore all possible combinations of operators and numbers formed from the input string.

Determine the fewest number of subsequences from a source string needed to construct a target string. Each subsequence must match a portion of the source string.

Rearrange the characters in a given string such that no two adjacent characters are the same. If such an arrangement is possible, return it; otherwise, return an empty string.

Determine if one string is a subsequence of another. That is, check if you can form the first string by deleting characters from the second string without changing the order of the remaining characters.

Design a search autocomplete system that suggests relevant sentences based on user input. The system should efficiently return the top k most relevant sentences ranked by frequency.

Find the longest word in a given dictionary that can be built one character at a time using other words in the dictionary. If there are multiple such words, return the lexicographically smallest one.

You're given a list of numbers and how many times each number appears. Your task is to find the median value from this frequency distribution.

Multiply two sparse matrices represented as arrays of arrays. Optimize your solution to avoid unnecessary calculations on zero elements.

Given a set of coin denominations and a target amount, find the minimum number of coins needed to reach that amount. You can assume you have an unlimited supply of each coin type.

You're given a list of meeting times and need to figure out which room hosted the most meetings. Simulate the meeting schedules to track room usage and identify the busiest room.

Compress a given string by replacing consecutive repeating characters with the character followed by the count of repetitions. If the compressed string isn't shorter, return the original.

Given an array of numbers, can you find how many ways you can add a plus or minus sign before each number so that the sum of the entire array equals a specific target number?

Find the number of unique paths from the top-left to the bottom-right corner of a grid, but with obstacles blocking some paths. You need to navigate the grid avoiding the obstacles.