Qualcomm Coding Interview Questions

String Compression III

Given a string word, compress it using the following algorithm:

Reverse Linked List

Given the head of a singly linked list, reverse the list, and return the reversed list.

LRU Cache

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

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.

Remove Nth Node From End of List

Given the head of a linked list, remove the nth node from the end of the list and return its head.

Reverse Bits

Reverse bits of a given 32 bits signed integer.

Middle of the Linked List

Given the head of a singly linked list, return the middle node of the linked list.

Rotate Image

You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

Merge Sorted Array

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and num...

Number of 1 Bits

Given a positive integer n, write a function that returns the number of set bits in its binary representation (also known as the Hamming weight).

Two Sum

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

Climbing Stairs

You are climbing a staircase. It takes n steps to reach the top.

Palindrome Number

Given an integer x, return true if x is a palindrome, and false otherwise.

Majority Element

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

Valid Parentheses

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

Swap Nodes in Pairs

Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only...

Design Memory Allocator

You are given an integer n representing the size of a 0-indexed memory array. All memory units are initially free.

Implement Queue using Stacks

Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (push, peek, pop, an...

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.

Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

String to Integer (atoi)

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer.

Reverse Nodes in k-Group

Given the head of a linked list, reverse the nodes of the list k at a time, and return the modified list.

Length of Last Word

Given a string s consisting of words and spaces, return the length of the last word in the string.

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.

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...

Maximum Subarray

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

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.

Single Number

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.

Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1...

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...

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...

Kth Largest Element in an Array

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

Design Circular Queue

Design your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (First In Fi...

Trapping Rain Water II

Given an m x n integer matrix heightMap representing the height of each unit cell in a 2D elevation map, return the volume of water it can trap after raining.

Find Winner on a Tic Tac Toe Game

Tic-tac-toe is played by two players A and B on a 3 x 3 grid. The rules of Tic-Tac-Toe are:

Linked List Cycle

Given head, the head of a linked list, determine if the linked list has a cycle in it.

Longest Substring Without Repeating Characters

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

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...

Two Sum II - Input Array Is Sorted

Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number....

First Unique Character in a String

Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.

Power of Two

Given an integer n, return true if it is a power of two. Otherwise, return false.

Rectangle Overlap

An axis-aligned rectangle is represented as a list [x1, y1, x2, y2], where (x1, y1) is the coordinate of its bottom-left corner, and (x2, y2) is the coordinate...

Power of Four

Given an integer n, return true if it is a power of four. Otherwise, return false.

Is Subsequence

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

Maximum Depth of Binary Tree

Given the root of a binary tree, return its maximum depth.

Pow(x, n)

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