Salesforce Coding Interview Questions

Word Break

Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.

Subarray Product Less Than K

Given an array of integers nums and an integer k, return the number of contiguous subarrays where the product of all the elements in the subarray is strictly le...

String Compression

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

Distinct Subsequences

Given two strings s and t, return the number of distinct subsequences of s which equals t.

LFU Cache

Design and implement a data structure for a Least Frequently Used (LFU) cache.

Merge Intervals

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove...

LRU Cache

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache.

Group Anagrams

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

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.

Count the Number of Fair Pairs

Given a 0-indexed integer array nums of size n and two integers lower and upper, return the number of fair pairs.

Maximum Frequency Stack

Design a stack-like data structure to push elements to the stack and pop the most frequent element from the stack.

Height Checker

A school is trying to take an annual photo of all the students. The students are asked to stand in a single file line in non-decreasing order by height. Let thi...

Design a Text Editor

Design a text editor with a cursor that can do the following:

Palindromic Substrings

Given a string s, return the number of palindromic substrings in it.

Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without duplicate characters.

Beautiful Towers II

You are given a 0-indexed array maxHeights of n integers.

Course Schedule II

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...

Beautiful Towers I

You are given an array heights of n integers representing the number of bricks in n consecutive towers. Your task is to remove some bricks to form a mountain-sh...

Check Whether Two Strings are Almost Equivalent

Two strings word1 and word2 are considered almost equivalent if the differences between the frequencies of each letter from 'a' to 'z' between word1 and word2 i...

Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

Valid Parentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

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.

Trapping Rain Water

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.

Beautiful Arrangement

Suppose you have n integers labeled 1 through n. A permutation of those n integers perm (1-indexed) is considered a beautiful arrangement if for every i (1 <= i...

Kth Largest Element in an Array

Given an integer array nums and an integer k, return the kth largest element in the array.

Binary Tree Maximum Path Sum

A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequ...

Largest Number

Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.

Maximum Product of Three Numbers

Given an integer array nums, find three numbers whose product is maximum and return the maximum product.

Asteroid Collision

We are given an array asteroids of integers representing asteroids in a row. The indices of the asteroid in the array represent their relative position in space...

Integer to Roman

Seven different symbols represent Roman numerals with the following values:

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.

Task Scheduler

You are given an array of CPU tasks, each labeled with a letter from A to Z, and a number n. Each CPU interval can be idle or allow the completion of one task....

Longest Palindromic Substring

Given a string s, return the longest palindromic substring in s.

Coin Change

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

Count Palindromic Subsequences

Given a string of digits s, return the number of palindromic subsequences of s having length 5. Since the answer may be very large, return it modulo 109 + 7.

Minimum Window Substring

Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is inc...

Min Stack

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

Validate Binary Search Tree

Given the root of a binary tree, determine if it is a valid binary search tree (BST).

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.

Decode Ways

You have intercepted a secret message encoded as a string of numbers. The message is decoded via the following mapping:

Maximal Square

Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.

Partition Array Into Two Arrays to Minimize Sum Difference

You are given an integer array nums of 2 n integers. You need to partition nums into two arrays of length n to minimize the absolute difference of the sums of t...

Jump Game

You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length...

Decode String

Given an encoded string, return its decoded string.

Search in Rotated Sorted Array

There is an integer array nums sorted in ascending order (with distinct values).

Daily Temperatures

Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait aft...

Reconstruct Original Digits from English

Given a string s containing an out-of-order English representation of digits 0-9, return the digits in ascending order.

Is Subsequence

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

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...

Max Area of Island

You are given an m x n binary matrix grid. An island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume al...

Container With Most Water

You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).

Capacity To Ship Packages Within D Days

A conveyor belt has packages that must be shipped from one port to another within days days.

IPO

Suppose LeetCode will start its IPO soon. In order to sell a good price of its shares to Venture Capital, LeetCode would like to work on some projects to increa...

Count Binary Substrings

Given a binary string s, return the number of non-empty substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in these substrings...

Degree of an Array

Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.

Product of Array Except Self

Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].

Maximize Greatness of an Array

You are given a 0-indexed integer array nums. You are allowed to permute nums into a new array perm of your choosing.

Populating Next Right Pointers in Each Node

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:

House Robber

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob...

Roman to Integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

Construct Binary Tree from Preorder and Inorder Traversal

Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, c...

First Missing Positive

Given an unsorted integer array nums. Return the smallest positive integer that is not present in nums.

Merge k Sorted Lists

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.

Wildcard Matching

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '' where:

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...

Move Zeroes

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Rotting Oranges

You are given an m x n grid where each cell can have one of three values:

Lowest Common Ancestor of a Binary Tree

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

Maximum Difference Between Increasing Elements

Given a 0-indexed integer array nums of size n, find the maximum difference between nums[i] and nums[j] (i.e., nums[j] - nums[i]), such that 0 <= i < j < n and...

Serialize and Deserialize Binary Tree

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitte...

Kth Smallest Element in a Sorted Matrix

Given an n x n matrix where each of the rows and columns is sorted in ascending order, return the kth smallest element in the matrix.

Smallest Subtree with all the Deepest Nodes

Given the root of a binary tree, the depth of each node is the shortest distance to the root.

2 Keys Keyboard

There is only one character 'A' on the screen of a notepad. You can perform one of two operations on this notepad for each step:

Flatten Binary Tree to Linked List

Given the root of a binary tree, flatten the tree into a "linked list":

The Skyline Problem

A city's skyline is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. Given the locations and heights of...

Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right, which minimizes the sum of all numbers along its path.

Pairs of Songs With Total Durations Divisible by 60

You are given a list of songs where the ith song has a duration of time[i] seconds.

Best Time to Buy and Sell Stock II

You are given an integer array prices where prices[i] is the price of a given stock on the ith day.

Different Ways to Add Parentheses

Given a string expression of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. Y...

Insert Delete GetRandom O(1)

Implement the RandomizedSet class:

N-Queens

The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.

Stream of Characters

Design an algorithm that accepts a stream of characters and checks if a suffix of these characters is a string of a given array of strings words.

Triangle

Given a triangle array, return the minimum path sum from top to bottom.

Longest Valid Parentheses

Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.

Sort Colors

Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order...

Number of Matching Subsequences

Given a string s and an array of strings words, return the number of words[i] that is a subsequence of s.

Subsets

Given an integer array nums of unique elements, return all possible subsets (the power set).

Majority Element II

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times.

Count Primes

Given an integer n, return the number of prime numbers that are strictly less than n.

Majority Element

Given an array nums of size n, return the majority element.

Predict the Winner

You are given an integer array nums. Two players are playing a game with this array: player 1 and player 2.

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Reverse Words in a String III

Given a string s, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.