Weed Out Questions

Question 1

Find Second Highest Salary (SQL)

Answer 1

SELECT MAX(Salary) From Employee where Salary Not In (SELECT MAX(Salary From Employee

Question 2

Difference between GET and POST (HTTP)

Answer 2

GET retrieves data from the server and POST creates/updates. POST is different that PUT in that calling POST multiple times creates multiple instances of same data. GET is in URL, POST is in HTML Forms

Question 3

Difference between a Class and an object

Answer 3

Class defines the structure, methods, initial values etc. and an object is an instance of a class

Question 4

FizzBuzz

Answer 4

1-100, multiples of 3: “Fizz”, multiples of 5: “Buzz”, multiples of 3 and 5 “FizzBuzz”

Question 5

Fibonocci Sequence in different optimization iterations

Answer 5

Brute force, Recursion, Dynamic Programming, Store last two numbers

Question 6

Add, Remove, Insert elements from a LinkedList

Answer 6

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Question 7

Find the middle element of a linked list in one pass

Answer 7

Maintain two pointers with one increment by two and the other by one

Question 8

Find the kth element in one pass

Answer 8

Two pointers, when one reaches the kth element, start the other

Question 9

In an integer array 1 to 100 find the duplicate number

Answer 9

Total sum should be equal to n(n+1)/2 so simply subtract actual sum from expected sum

Question 10

Reverse a string

Answer 10

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Question 11

Sort an array with bubble sort

Answer 11

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Question 12

Difference between stack and queue

Answer 12

LIFO, FIFO

Question 13

Find duplicates in an array if there are more than one duplicate

Answer 13

Store each element in a hashmap as a key with the number of occurrences as a value

Question 14

Difference between singly and doubly linked list

Answer 14

Singly linked has one pointer to the next node, doubly has two pointers

Question 15

Check if a number is a palindrome

Answer 15

For reference: 1234/10 will give you 123 and 1234%10 will return 4

Question 16

What is a binary search tree

Answer 16

Left node has values less than root right has keys that are greater node value than root?

Question 17

Reverse a linked list using recursion and iteration

Answer 17

prev = None
        current = self.head 
        while(current is not None): 
            next = current.next
            current.next = prev 
            prev = current 
            current = next
        self.head = prev 
https://www.geeksforgeeks.org/reverse-a-linked-list/