David Lowes - Portfolio

Cracking the coding interview

A list of solutions to commonly asked coding interview questions

General

Arrays

Find the most frequent integer in an array

Find the common elements of 2 int arrays

Find the only element in an array that only occurs once.

Implement binary search of a sorted array of integers

Find the min/max integers in an array

Bit Manipulation: Lonely Integer

Strings

Reverse a String iteratively and recursively

Determine if 2 Strings are anagrams

Check if String is a palindrome

Check if a String is composed of all unique characters

Determine if a String is an int or a double

Find the length of the shortest word in a String

Print all permutations of a String

Implement Facebook's 'like' function using strings

Write number is expanded form

Trees

Implement a BST with insert and delete functions

Print a tree using BFS and DFS

Write a function that determines if a tree is a BST

Find the smallest element in a BST

Find the 2nd largest number in a BST

Given a binary tree which is a sum tree (child nodes add to parent), write an algorithm to determine whether the tree is a valid sum tree

Find the distance between 2 nodes in a BST and a normal binary tree

Print the coordinates of every node in a binary tree, where root is 0,0

Print a tree by levels

Given a binary tree which is a sum tree, write an algorithm to determine whether the tree is a valid sum tree

Given a tree, verify that it contains a subtree.

Find the max distance between 2 nodes in a BST.

Construct a BST given the pre-order and in-order traversal Strings

Stacks, Queues, and Heaps

Implement a stack with push and pop functions

Implement a queue with queue and dequeue functions

Find the minimum element in a stack in O(1) time

Write a function that sorts a stack (bonus: sort the stack in place without extra memory)

Implement a binary min heap. Turn it into a binary max heap

Implement a queue using 2 stacks

Linked Lists

Implement a linked list (with insert and delete functions)
Find the Nth element in a linked list
Remove the Nth element of a linked list
Check if a linked list has cycles
Given a circular linked list, find the node at the beginning of the loop. Example: A->B->C->D->E->C, C is the node that begins the loop
Check whether a link list is a palindrome
Reverse a linked list iteratively and recursively

Sorting

Implement bubble sort
Implement selection sort
Implement insertion sort
Implement merge sort
Implement quick sort

Get in touch

I would love to hear from you. If you have an idea, want me to work for you or just want to hang and grab a coffee, please contact me using the form or email below. Muchos Gracia.

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