Pinterest Coding Interview Questions

Count and Say

The count-and-say sequence is a sequence of digit strings defined by the recursive formula:

Reconstruct Itinerary

You are given a list of airline tickets where tickets[i] = [fromi, toi] represent the departure and the arrival airports of one flight. Reconstruct the itinerar...

Shortest Path in a Grid with Obstacles Elimination

You are given an m x n integer matrix grid where each cell is either 0 (empty) or 1 (obstacle). You can move up, down, left, or right from and to an empty cell...

Count Subarrays With Score Less Than K

The score of an array is defined as the product of its sum and its length.

Maximum Profit in Job Scheduling

We have n jobs, where every job is scheduled to be done from startTime[i] to endTime[i], obtaining a profit of profit[i].

Bus Routes

You are given an array routes representing bus routes where routes[i] is a bus route that the ith bus repeats forever.

Expression Add Operators

Given a string num that contains only digits and an integer target, return all possibilities to insert the binary operators '+', '-', and/or '' between the digi...

Find Median from Data Stream

The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value, and the median is the mean of the two midd...

Is Subsequence

Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

Reorganize String

Given a string s, rearrange the characters of s so that any two adjacent characters are not the same.

Longest Word in Dictionary

Given an array of strings words representing an English Dictionary, return the longest word in words that can be built one character at a time by other words in...

Jump Game III

Given an array of non-negative integers arr, you are initially positioned at start index of the array. When you are at index i, you can jump to i + arr[i] or i...

Coin Change

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.

Find K-th Smallest Pair Distance

The distance of a pair of integers a and b is defined as the absolute difference between a and b.

Meeting Rooms III

You are given an integer n. There are n rooms numbered from 0 to n - 1.

String Compression

Given an array of characters chars, compress it using the following algorithm:

Target Sum

You are given an integer array nums and an integer target.

Unique Paths II

You are given an m x n integer array grid. There is a robot initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-r...

Minimize Result by Adding Parentheses to Expression

You are given a 0-indexed string expression of the form "<num1>+<num2>" where <num1> and <num2> represent positive integers.

Is Graph Bipartite?

There is an undirected graph with n nodes, where each node is numbered between 0 and n - 1. You are given a 2D array graph, where graph[u] is an array of nodes...

Unique Paths III

You are given an m x n integer array grid where grid[i][j] could be:

The Number of Weak Characters in the Game

You are playing a game that contains multiple characters, and each of the characters has two main properties: attack and defense. You are given a 2D integer arr...

Single Element in a Sorted Array

You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.

Letter Combinations of a Phone Number

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

Combination Sum

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum...

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.

Possible Bipartition

We want to split a group of n people (labeled from 1 to n) into two groups of any size. Each person may dislike some other people, and they should not go into t...

Top K Frequent Elements

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.

Split Array Largest Sum

Given an integer array nums and an integer k, split nums into k non-empty subarrays such that the largest sum of any subarray is minimized.

Accounts Merge

Given a list of accounts where each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are...

Find Minimum Time to Finish All Jobs

You are given an integer array jobs, where jobs[i] is the amount of time it takes to complete the ith job.

Smallest Range Covering Elements from K Lists

You have k lists of sorted integers in non-decreasing order. Find the smallest range that includes at least one number from each of the k lists.

Find First and Last Position of Element in Sorted Array

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.

Implement Trie (Prefix Tree)

A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various appl...

Snakes and Ladders

You are given an n x n integer matrix board where the cells are labeled from 1 to n2 in a Boustrophedon style starting from the bottom left of the board (i.e. b...

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.

Shortest Path to Get All Keys

You are given an m x n grid grid where:

Sudoku Solver

Write a program to solve a Sudoku puzzle by filling the empty cells.