Validate Binary Search Tree

It is a gloomy day in the Twin Cities of Minneapolis and St. Paul. The good thing is that we have about two days until Thanksgiving Day 2020. This year we are cooking an 11 lbs. turkey. Typically my wife and I make an 18+ lbs. bird. Not only that but we are dropping half of it at our granddaughters place. On Thanksgiving Day we will be connecting with family via Jitsi and Skype. Continue reading “Validate Binary Search Tree”

Construct Binary Search Tree from Pre Order Traversal

It is Thanksgiving Week 2020 and we do not have a winner in the 2020 Presidential Elections yet. The amount of fraud in this year’s elections has been unprecedented. My comment has nothing to do with politics. It is just based on common sense for individuals 12 years of age and older. I have friends and relatives living in different parts of the world. Their confidence and respect in the USA is almost (never generalize) gone.

On multiple occasions and referring to different topics, I have mentioned in this blog a technique used when people want to understand the positions of each other. First both argue on behalf of their own positions. Then, and this is the key of the technique, they switch positions and argue in favor of the opposite position. It is amazing what you can learn about different ideas when you use this technique. The reason for this tends to be based on facts and logic. Continue reading “Construct Binary Search Tree from Pre Order Traversal”

Binary Search Tree to Greater Sum Tree – Java

Hello there. It is another Sunday morning during the COVID-19 pandemic. The current temperature in the Twin Cities of Minneapolis and St. Paul is about 30F and is sunny. As soon as I finish with this post my wife and I will stop by Target to get some sundries.

Yesterday my wife and I met my older son at Costco in Minneapolis. We get together every other weekend at Costco to do groceries. My wife and I got a 35 lbs. of beef chuck cut. Once we got home we cut smaller manageable portions, put them in bags and placed them in the freezer. We left one portion out. We cut it into smaller pieces, cut some potatoes, onions, garlic and carrots. Put them in a tray in a 550 degree oven for 10 minutes. The beef browned quite nicely. We then put the items in a pressure cook with some water and left them cooking for 1 ½ hours. We served them in on a thin base of very hot brown rice. I had two large servings. It was delicious. Continue reading “Binary Search Tree to Greater Sum Tree – Java”

Minimum Distance Between BST Nodes

Earlier today I read the article “Changing the clocks is a bad idea — and it should end, sleep experts say” by Jen Smith, CNN. The article makes a case for the USA to eliminate daylight savings time. It seems there is enough science behind the idea.

I am a morning person. I have a wake up alarm in my smart phone to wake up at 06:00 AM every day. Most of the time I get up about an hour early. Of course, in the evenings my wife and I are ready to hit the sack around 08:00 PM. At the start of summer the sun is up before 06:00 AM. At the start of winter, it is dark around 04:30 PM. Continue reading “Minimum Distance Between BST Nodes”

Lowest Common Ancestor in Binary Search Tree

It is a beautiful sunny summer day in the Twin Cities of Minneapolis and St. Paul. The high temperature for today in the city I live is forecasted to be 83 F. I prefer high temperatures in the range of 75 F to 80 F, but 83 F will have to do.

Yesterday I spent a few hours in front of my computers. My wife left early with a friend to go walking and shopping. My wife got back shortly after 11:00 AM. We made some potatoes with veggies in the grill using a cast iron pan. We always add some pepper, salt and a splash of oil with a high smoke point (i.e., avocado or peanut). Continue reading “Lowest Common Ancestor in Binary Search Tree”

Family Names

Yesterday my wife had an appointment at the hair salon. The gal that cut her hair commented that there were more people than usual complaining of seasonal allergies; some of them have never before experienced symptoms. My wife and I have some light allergies every season. Some days this year we have experienced strong symptoms. Hopefully things will get better soon.

Last evening in the local news, it was mentioned that due to the amount of water due to rain and melted snow, farmers are a couple weeks behind planting their crops. Having grains and vegetables is more important than experiencing allergy symptoms. Hopefully all will turn out well as the season progresses. The forecast for today calls for strong rain starting around mid morning and ending early tomorrow. Most of the rivers in this area are at or above normal flood levels. Hope the forecast falls short in moisture.

This week I had the opportunity to talk with a fellow software developer. We briefly discussed the approach of traversing a data structure using loops and recursion. It seems that if the number of objects is relatively small, recursion is elegant approach. That said, for large number of objects, recursion may fail due to execution stack limitations. Continue reading “Family Names”

Is this a Binary Search Tree

I took a look at the “Is This a Binary Search Tree?” challenge at HackerRank. If interested in learning about this challenge and associated requirements use the following URL:  https://www.hackerrank.com/challenges/ctci-is-binary-search-tree

The idea is quite simple. A BST should have all nodes in an ascending order when traversed using an in order traversal algorithm. If they do not, a value in a node is out of order rendering the tree as an invalid BST. Continue reading “Is this a Binary Search Tree”

AVL Tree

binary_search_treeYesterday I was looking at a problem on the HackerRank web site. The title is “Self Balancing Tree”. The challenge is to write the insert() function / method in such a way to insert new elements and keep the binary search tree balanced. As usual, no matter how familiar the subject might be, I always research the subject before planning a solution. By doing so I refresh my knowledge and in many cases learn one or more things.  To research I try to use Google research and go for Wikipedia articles.  Based on what I find I tend to go into different on-line articles or books. Continue reading “AVL Tree”