Flatten a Multilevel Doubly Linked List

Good morning software developers and software engineers! Hope your day has started on the right note. Every morning, weather allowing for it, my wife and I have breakfast and go for a brisk walk. Today was no exception. Before 08:00 AM I have watered plants in the yard including a rosemary bush that we planted a week ago or so, showered, shaved, got dressed and started my work day. It is amazing how well you feed during the day once you have exercised, no matter how short or long.

Last week I read the article (let me see if I can find it in my Twitter account @john_canessa … found it) Cybersecurity bills gain new urgency after rash of attacks. It seems that both political parties, Democrats and Republicans are pushing a bill that will help our country against cyber attacks. In the past few months we have seen hundreds if not thousands of attacks, some to disable our government, companies and organizations or to ask for ransom. One of the proposed ideas is to force targets to disclose in a short period of time (24 hours or so) any cyber breach they have experienced. This will allow the government and other organizations to take action as needed to prevent the same type of attacks. In my opinion there should be some type of penalty for the bad actors in an attempt to curb their proliferation (transparency and accountability). Will see what happens with the bill and its implementation! Continue reading “Flatten a Multilevel Doubly Linked List”

Unique Binary Search Trees

It has been raining all day in the Twin Cities of Minneapolis and St. Paul. The good thing is that there has been little lightning. I was going to replace an old UPS that I am using to power my main computer in which I develop all the code for this blog, but it was not necessary. I will replace the UPS over the weekend. Continue reading “Unique Binary Search Trees”

Count Sub Islands

It is Thursday July 01, 2021 in the Twin Cities of Minneapolis and St. Paul. The forecast called for a sunny day but clouds have rolled in and out. Hopefully it will not rain.

After having breakfast, my wife and I went out on our daily walk. We run into several people we know. Perhaps people want to get in their workout before heading out for the long weekend. The fourth of July falls this Sunday, so the observed Independence Day (United States) is Monday July 05, 2021.

We do not have plans for the holiday. We will stick to our daily routine. I will try to get in one or two work-blocks each day in addition to do groceries and visit the Farmers Market in St. Paul. For one reason or another this year we have not shopped there yet. Continue reading “Count Sub Islands”

Generate Parentheses

For lunch my wife made a pork and cauliflower dish. She added a few drops of Green Dragon Hot Sauce. It goes very well with pork dishes. For desert we had gypsy arm filled in with dulce de leche with strawberries on the side. Lunch was quite good. After chatting for a few and doing the dishes and pots I got back to my home office. Continue reading “Generate Parentheses”

Symmetric Tree

Good morning gals and guys! Hope you day has started on the right note. Today in the Twin Cities of Minneapolis and St. Paul we are expecting a high temperature of 67F and the day is sunny. Starting today the two-week forecast shows high temperatures in the upper 60’s to mid to lower 70’s. All looks nice, but we are somewhat low on precipitation. From my backyard I can see a small pond with very low water levels. Hopefully farmers are receiving enough rain to have a good crop this fall.

This morning I watched a session from AWS Summit Online. The session is named “Amazon DynamoDB: Untold stories of databases in a serverless world” by Angela Timofte. She is a data platform manager with Trustpilot. What called my attention were a set of points she brought up which illustrates how important is to allow your technical staff to experiment, learn and make mistakes. Such approach has helped the company move from MySQL to MongoDB and currently to DynamoDB. What is more important, the company currently uses about ten different database engines to store different types of data. They are using the right tools for the jobs (one size does not fit all). If you get a chance take a look at the 22 minute presentation here. Continue reading “Symmetric Tree”

Binary Tree Pruning

Have an on-line call at 02:30 PM. I believe I am well prepared. Will see how it goes.

Earlier today I selected LeetCode 814 Binary Tree Pruning problem.

We are given the head node root of a binary tree, 
where additionally every node's value is either a 0 or a 1.

Return the same tree where every subtree (of the given tree) 
not containing a 1 has been removed.

(Recall that the subtree of a node X is X, plus every node that is a descendant of X.)

Note:

o The binary tree will have at most 200 nodes.
o The value of each node will only be 0 or 1.

We are given a binary tree whose nodes are holding 0 or 1 as value. We need to prune the BT as described in the requirements. If you are interested in this problem please navigate to the LeetCode web site and read the actual requirements. In addition LeetCode has a set of test cases.

In this post we will solve the problem using the Java programming language on a Windows 10 computer using the VSCode IDE. You can use any of the languages supported by LeetCode and solve the problem on the LeetCode side with the IDE provided. Continue reading “Binary Tree Pruning”

All Elements in Two Binary Search Trees

The temperature in the Twin Cities of Minneapolis and St. Paul continues to oscillate between negative and positive values in the Fahrenheit scale. The good thing is that we are around mid February. This year spring starts Saturday March 20. That is about 6 to 7 weeks from today. Continue reading “All Elements in Two Binary Search Trees”

Merge Sort in Java

Today is January 20, 2021 and is the United States presidential inauguration. Not sure what to expect today or in the following days. Hope all goes well and we can move forward. I believe most of the people in our country are tired of reading and watching political news and propaganda.

Yesterday I attended an ACM webinar “Agent-Human Collaboration and Learning for Improving Human Satisfaction” by Sarit Kraus. She is a professor of computer science at the Bar-Ilan University in Israel.

What called my attention was the concept of having agents for both the automation and the human. I can easily see how that would work in a healthcare or a disaster scenario I do not see how that could work well with autonomous cars. I will go over the slides tomorrow and see if I missed something; otherwise I will send her a message. Hopefully she will have time to respond. Will let you know my findings. Continue reading “Merge Sort in Java”

Encrypted Words

Today is Friday. The current temperature is about 40 F which is not bad for this time of the year. Tomorrow is my youngest sister birthday. I believe she is still in China. I will send her a message wishing her a nice day.

I have a few problems solve from a Facebook coding practice questions site. I should post them over the weekend if something else does not come up. My wife and I are planning on getting groceries done at the end of the day so we can remain at home over the weekend. Grocery stores tend to have much more activity on weekends. Continue reading “Encrypted Words”

Print Immutable Linked List in Reverse

Hi gals and guys. Hope you are doing well during the COVID-19 pandemic. It seems that most of us are somewhat tired following the basic rules that reduce the spread of the coronavirus. By relaxing the rules in the past few months, the numbers of COVID-19 infections, in most cities worldwide, are going up. Note that the issue is the number of infections, not the number of deaths. Infected people may need hospital services. If the number of patients is larger than the capacity like it was when this thing started, then we have a problem. At this point in time, people with most infections per 1,000, is people in college age. Please follow the rules! We all benefit from it. Continue reading “Print Immutable Linked List in Reverse”