Disjoint Union Sets

It is a rainy Sunday morning in the Twin Cities of Minneapolis and St. Paul. Rain started last evening around 08:00 PM and according to the weather forecast will subside later tonight around 10:00 PM. Not a nice day to be outdoors or grilling.

Last Friday my son mentioned that he would be going shopping on Saturday morning to the Costco Minneapolis Business Center Warehouse. My wife and I decided to join him at 07:00 AM (opening time). We met in the parking lot, donned our gloves and mask, and headed in. We have been at the Restaurant Depot many times, but were nicely surprised with the size of the Costco facility and the variety of items. From now on my wife and I will make the trip from home (30 minutes about 20 miles away) a couple times a month to the Costco in Minneapolis. We believe it is worth the drive.

My wife and I cook and bake. I like to bake deserts, breads and Italian cuisine. My wife cooks lunch during the workdays. We both cook on weekends. We have breakfast which I prepare every day and we both skip dinner. The point that I am trying to make is that we did not start cooking or baking due to the coronavirus pandemic.

Last week we noticed that we were running very low on yeast. We went grocery shopping last Tuesday morning and where not able to find yeast at Costco in Eagan, MN or Trader Joe’s in St. Paul. Back home, I went to Amazon.com and ordered a 2 pound pouch of Red Star dry yeast. The total after taxes (we do have Amazon Prime) came to $24.99 USD. I thought it was expensive but it seems that every one and their brother are baking now a day. The delivery will be sometime tomorrow (Monday).

While at Costco we found lots of Red Star dry yeast in the same 2 lb pouches we ordered from Amazon. That is the same yeast we have been using for over a decade. What we found disgusting was that Costco had the same 2 lb pouches of yeast for under $4.50 USD each. We bought two pouches (totaling 4 lbs) for about $9.00 USD. They should last a year or so. Continue reading “Disjoint Union Sets”

Sherlock and Anagrams

The news is full of articles and posts about the corona virus. Before getting in panic mode, stop by the CDC “Coronavirus Disease 2019 (COVID-19)” web page and get informed.

My wife and I follow and watch several YouTube channels. We are mostly interested in foods to prepare and consume and places to visit on our next holiday. Yesterday we watched a new episode on one channel that deals with food and travel in Sicily, Italy. The channel is hosted by a couple of Americans that have roots in Europe and Italy.

They had some interesting facts about how to make a disinfectant using alcohol, aloe vera and some scents. I was not going to mention the specific video, but as I am going over this post, I feel that it is missing. The video is named “SPECIAL EDITION: Coronavirus update from Sicily!”. Quite appropriate for the times we are living in. Continue reading “Sherlock and Anagrams”

A or B

Over the weekend I watched the YouTube video “Dealing with Negative Comments | AMA #3 – Ask Me Anything with Lex Fridman”. I have watched a few of his videos. I do enjoy them to the point that I have subscribed to them. There is one in which Lex interviews Donald Knuth and other where he interviews Andrew Ng. Both videos are over an hour so I will watch them over the weekend.

If you are interested in getting information about Lex Fridman you can find it here or there.

I picked the challenge “A or B” from HackerRank after receiving an email message. I guess that if you solve a few of their problems they like you to continue visiting their site and solving additional challenges. I like to work on one or two a week. I believe it is the only way to learn and / or refresh material. Continue reading “A or B”

Shuffle Array – Java

Every work day when quitting time approaches (around 05:00 PM) I check my to-do list. One thing I had for the day was to check is there is a method in a Java class to shuffle the contents of an array. This is a nice mechanism to have in your toolbox. For example, if you want to load a binary tree search (BST) and the data is sorted, the tree will basically load like a linked list. In a BST you can typically find an element in O(log(n)). But if the elements were inserted sorted, the search is performed in O(n) which is slower than O(log(n)). In such cases you can just shuffle the array and then load the BST. Continue reading “Shuffle Array – Java”

Binary Tree Sum

In this post we will develop a couple methods to collect some information from a binary tree. The first method will be the base, and the second will be an enhancement of the first.

The first requirement is:  given a binary tree with double values, compute the sum of all nodes in the tree.

The second requirement is:  given a binary tree with double values, compute the sum of all nodes whose values are in a specified range (e.g., [ 10.0 : 15.0 ]). Continue reading “Binary Tree Sum”

The Full Counting Sort

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Today I decided to solve a HackerRank problem. Randomly I selected The Full Counting Sort. If interested read the requirements. I read the requirements and decided to give it a try.

Based on my experience with this problem you might want to follow my advice. Work on the algorithm and make sure it passes the two sample test cases. Once you are done, submit your solution. If you have a valid approach then chances are that your solution will fail test #5, it will time out. I generated up to three different versions of the countSort() function. I could not get past test #5 because it would time out. I spent time reading the discussions and they did not make much sense. I even bought test #5 for some hackos. By the way, the test includes 1,000,000 strings which I could not download no matter how many times I tried. With this problem do not purchase test #5. You will not be able to run it. Continue reading “The Full Counting Sort”

Sum of Two

I received a notification via email that Nicholas White had put a new video in YouTube. If you are interested, the video is named Google Coding Interview Question – Sum of Two. I enjoy working on problems. Try to get a few each week.

Let’s skip the chit chat and go directly to this problem. The statement for the problem follows:

You have two integer arrays a and b, and an integer target value v.

Determine whether there is a pair of numbers, where one number is taken from a and the other from b, that can be added together to get a sum of v.

Return true if such a pair exists, otherwise return false. Continue reading “Sum of Two”

First Duplicate

This morning in the Twin Cities of Minneapolis and St. Paul we woke up with a temperature of -11 F. The central heating unit worked overtime last night. It was quite dry indoors. Not sure why this happens due to the fact that the central heating as a built in humidifier and air exchange sub systems.

Yesterday morning I read the article “Do You Solve Programming Problems or Complete Exercises? (The Difference Matters.)” by Amy Haddad. She makes a difference between problem-solving and solving exercises. I agree with her interpretation. If interested read her article and possibly comment in her or my post.

Yesterday evening, I was browsing YouTube and ran into the video “Google Coding Interview Question – firstDuplicate” by Nicholas White. Continue reading “First Duplicate”

Cipher

I was somewhat busy over the weekend. My wife and I were going to make some cannoli but for simplicity we decided to bake some chocolate cornetto. We are planning on making cannoli next weekend.

Last week I was reading the web page from Microsoft Dynamics 365 Connected Store. It uses video cameras and IoT devices to capture non-PII (Personally Identifiable Information) from customers that can be used by the store to improve service and increase sales. I spend time reading different related articles and watching YouTube videos. I am impressed with the approach to the subject by Microsoft. Most companies try to incorporate PII data but that may have many implications for the store, customer and the ability to offer the system to customers in different parts of the world due to local laws. I can go on and on but that would take us out of the topic for this post. Continue reading “Cipher”

AND Product

Yesterday morning I watch most of the Association for Computing Machinery (ACM) webinar “OOPS! Learning from Surprise at Netflix”. The presenter was Lorin Hockstein who is a senior software engineer at Netflix. For what I was able to get out from the presentation is that when an issue in production appears, it is important to learn from it to make sure the code is updated to prevent the issue from ever happening again. That may require from simple changes to deeper design or even architectural modifications. Continue reading “AND Product”