Morgan Stanley Coding Interview Questions

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.

Best Team With No Conflicts

You are the manager of a basketball team. For the upcoming tournament, you want to choose the team with the highest overall score. The score of the team is the...

Minimum Cost to Move Chips to The Same Position

We have n chips, where the position of the ith chip is position[i].

Find The Original Array of Prefix Xor

You are given an integer array pref of size n. Find and return the array arr of size n that satisfies:

The Employee That Worked on the Longest Task

There are n employees, each with a unique id from 0 to n - 1.

Find the Longest Valid Obstacle Course at Each Position

You want to build some obstacle courses. You are given a 0-indexed integer array obstacles of length n, where obstacles[i] describes the height of the ith obsta...

Find Subarrays With Equal Sum

Given a 0-indexed integer array nums, determine whether there exist two subarrays of length 2 with equal sum. Note that the two subarrays must begin at differen...

Count Subarrays With Fixed Bounds

You are given an integer array nums and two integers minK and maxK.

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...

Two Sum

Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target.

First Missing Positive

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

Longest Substring Without Repeating Characters

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

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.

Kth Largest Element in an Array

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

Group Anagrams

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

LRU Cache

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

Minimum Number of Refueling Stops

A car travels from a starting position to a destination which is target miles east of the starting position.

Copy List with Random Pointer

A linked list of length n is given such that each node contains an additional random pointer, which could point to any node in the list, or null.

Make K-Subarray Sums Equal

You are given a 0-indexed integer array arr and an integer k. The array arr is circular. In other words, the first element of the array is the next element of t...

Contiguous Array

Given a binary array nums, return the maximum length of a contiguous subarray with an equal number of 0 and 1.

Decode Ways

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

Word Search

Given an m x n grid of characters board and a string word, return true if word exists in the grid.

Rotate List

Given the head of a linked list, rotate the list to the right by k places.

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.

Coin Change II

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

Kth Missing Positive Number

Given an array arr of positive integers sorted in a strictly increasing order, and an integer k.

Minimum Operations to Reduce X to Zero

You are given an integer array nums and an integer x. In one operation, you can either remove the leftmost or the rightmost element from the array nums and subt...

Palindrome Linked List

Given the head of a singly linked list, return true if it is a palindrome or false otherwise.

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...

Min Stack

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

Count of Integers

You are given two numeric strings num1 and num2 and two integers maxsum and minsum. We denote an integer x to be good if:

Subtree of Another Tree

Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false oth...

Reverse String

Write a function that reverses a string. The input string is given as an array of characters s.

Subarrays with K Different Integers

Given an integer array nums and an integer k, return the number of good subarrays of nums.

Remove Duplicates from Sorted Array

Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order o...

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...

Valid Parentheses

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

Reverse Words in a String

Given an input string s, reverse the order of the words.

Longest Palindromic Substring

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

Maximum Subarray

Given an integer array nums, find the subarray with the largest sum, and return its sum.

Subarray Sum Equals K

Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.

Steps to Make Array Non-decreasing

You are given a 0-indexed integer array nums. In one step, remove all elements nums[i] where nums[i - 1] > nums[i] for all 0 < i < nums.length.

Count of Range Sum

Given an integer array nums and two integers lower and upper, return the number of range sums that lie in [lower, upper] inclusive.

Stamping The Sequence

You are given two strings stamp and target. Initially, there is a string s of length target.length with all s[i] == '?'.

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...

Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

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.

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...

Next Greater Element I

The next greater element of some element x in an array is the first greater element that is to the right of x in the same array.