Charles Schwab Software Developer Intern Interview Questions and Answers

Code for rand7 using rand5 function

• Use rand5 twice to generate a number in [1,25] with equal probability

• If the number is greater than 21, discard and try again

• Otherwise, return (number mod 7) + 1

LRU cache is implemented using a doubly linked list and a hash map.

• Create a doubly linked list to keep track of the order of elements in the cache.

• Create a hash map to store the key-value pairs of the cache.

• When a new element is added, check if the cache is full. If it is, remove the least recently used element from the linked list and the hash map.

• When an element is accessed, move it to the front of the linked list to...read more

Function to randomly select pivot element in Quick Sort

• Generate a random index within the range of the array

• Return the element at the randomly generated index as the pivot

ATM transaction involves multiple background processes including authentication, authorization, and communication with bank servers.

• Customer inserts card and enters PIN

• ATM authenticates the card and PIN

• ATM requests authorization from bank server

• Bank server verifies account balance and approves or denies transaction

• ATM dispenses cash or completes other requested transaction

• ATM updates account balance and sends transacti

Cut cake into 8 pieces using knife 3 times only.

• First, cut the cake horizontally into two equal halves.

• Then, cut the cake vertically into four equal pieces.

• Finally, cut the cake horizontally again into eight equal pieces.

• Make sure to use the knife efficiently to minimize the number of cuts.

• Practice visualization before making the cuts to avoid mistakes.

The one bird was already dead.

• The bird was already dead before the shot was fired.

• The bird was injured and unable to fly away with the rest of the birds.

• The bird was a decoy bird used for hunting purposes.

• The bird was a trained bird used for falconry.

Developed a web-based attendance management system and a mobile app for event management.

• Created a database schema and implemented CRUD operations using PHP and MySQL.

• Designed the user interface using HTML, CSS, and JavaScript.

• Integrated Google Maps API for location tracking in the mobile app.

• Implemented push notifications using Firebase Cloud Messaging.

• Collaborated with a team of four to complete the projects within t

Finding smallest of 4 numbers without using >.< and min function in Java.

• Initialize a variable with the first number

• Compare it with the remaining numbers using if-else statements

• If a smaller number is found, update the variable

• Repeat until all numbers are compared

• The final value of the variable will be the smallest number

Code for palindrome checking

• Convert the input to lowercase to ignore case sensitivity

• Use two pointers, one at the start and one at the end of the string

• Compare the characters at both pointers and move them towards each other

• If all characters match, it's a palindrome

Javascript code to display 'Hello World!' on the webpage

• Create a new HTML file

• Add a script tag with 'type' attribute set to 'text/javascript'

• Inside the script tag, use document.write() to display 'Hello World!'

Swap two numbers without using a temporary variable.

• Use addition and subtraction to swap the values

• Use XOR operator to swap the values

• Use multiplication and division to swap the values

To add 2 tables, we need to use a join operation on a common column.

• Identify the common column between the tables

• Choose the appropriate join type (inner, outer, left, right)

• Write the SQL query to join the tables

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column

Union combines and removes duplicates, Union All combines all rows including duplicates.

• Union is used to combine the result sets of two or more SELECT statements and remove duplicates.

• Union All is used to combine the result sets of two or more SELECT statements and includes all rows, including duplicates.

• Union is slower than Union All as it has to remove duplicates.

• Union requires the same number of columns in all SELEC...read more

Being assigned a project with unrealistic deadlines and minimal guidance

• Received a project with tight deadlines and unclear requirements

• Struggled to meet the deadlines due to lack of guidance and support

• Had to work long hours and weekends to try to complete the project

• Learned the importance of clear communication and setting realistic expectations