## LeetCode 111. Minimum Depth of Binary Tree in Java

In this post we will solve LeetCode 111. Minimum Depth of Binary Tree problem using Java and the VSCode IDE on a Windows computer. Not that it matters, but I am using Windows 11.

```Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path
from the root node down to the nearest leaf node.

Note: A leaf is a node with no children.

Constraints:

o The number of nodes in the tree is in the range [0, 10^5].
o -1000 <= Node.val <= 1000

Related Topics:

o Tree
* Depth-First Search
o Binary Tree
```

We are given the root of a binary tree and are asked to find the minimum depth of the tree. A couple years ago we solved in this post Maximum Depth of a Binary Tree.

The definition of minimum depth is provided in the requirements for the problem at hand. Continue reading “LeetCode 111. Minimum Depth of Binary Tree in Java”

## LeetCode 1302. Deepest Leaves Sum in Java

In this post we will solve the LeetCode 1302. Deepest Leaves Sum problem using the Java programming language with the VSCode IDE on a Windows computer.

```Given the root of a binary tree,
return the sum of values of its deepest leaves.

Constraints:

o The number of nodes in the tree is in the range [1, 10^4].
o 1 <= Node.val <= 100

Related Topics:

o Tree
o Depth-First Search
o Binary Tree
```

We are given a binary tree and we need to return the sum of the values of all deepest leaves. Continue reading “LeetCode 1302. Deepest Leaves Sum in Java”

## LeetCode 872. Leaf-Similar Trees in Java

In this post we will be solving LeetCode 872. Leaf-Similar Trees. As usual, if interested, please visit the LeetCode site and read the current version of the problem to make sure all is well before you start developing code.

```Consider all the leaves of a binary tree,
from left to right order,
the values of those leaves form a leaf value sequence.

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

Constraints:

o The number of nodes in each tree will be in the range [1, 200].
o Both of the given trees will have values in the range [0, 200].

Related Topics:

o Tree
o Depth-First Search
o Binary Tree
```

We are given two binary trees. We need to determine if the sequence of leaf nodes match or not. Seems like an in-order tree traversal problem. We could populate a list with the leaf nodes of the first tree and repeat with the nodes of the second tree. Our answer will be based on the contents of both lists. Continue reading “LeetCode 872. Leaf-Similar Trees in Java”

## Sum of Nodes Between Two Nodes in Binary Tree

Good day!!! Hope all is going well for you. It is Friday and has been a very stressful week for me. Glad that the weekend is just around the corner.

Today we are going to cover a problem which a software engineer and I discussed earlier this week, but for some reason or the other, we did not generate code at the time. We just talked about it.

```We are given a binary tree with integer values and two different nodes in the binary tree,
we must return the sum of the values of the nodes that connect p and q inclusive.

Constraints:

o -1000 &lt;= val &lt;= 1000
o 2 &lt;= n &lt;= 200
```

As you can see, we are given a binary tree populated with integers. Do not recall if all integers were included. We will assume, since I am writing the requirements as we speak, that the values for the nodes are in the specified range and the number of nodes in the binary tree should not exceed the specified value. Continue reading “Sum of Nodes Between Two Nodes in Binary Tree”

## Binary Tree Upside Down

Today is Sunday. As usual I woke up at 06:00 AM and it was dark. I decided to stay in bed for a few minutes before getting up and fixing breakfast for my wife and me. The next thing was waking up around 06:45 AM. The day was clearing some, but still dark enough to require artificial light. I understand that if you fall asleep after your alarm clock goes off, that it is an indication from your body that you need additional sleep. That said; I do not recall doing much yesterday. Go figure!

As usual, for breakfast I make espresso on our Bialetti 6-cup Moka pot. Growing up my parents owned several Moka pots of different capacities. Some were used on a daily basis and others when my parents entertained family and friends. With time my mother started using a drip pot. She liked to get the first few drops and add some hot water. It was almost impossible to drink it straight up. Continue reading “Binary Tree Upside Down”

## Find Leaves of Binary Tree

Hi gals and guys! It is Friday afternoon and we have a long weekend ahead. Hope you enjoy Independence Day in the USA. The weather in my neck of the woods will be in the lower 90’s F thru Monday. On Tuesday the temperature will drop a few degrees and it seems we might receive some precipitation in the Twin Cities of Minneapolis and St. Paul.

On a separate note, it appears that the UPS attached to one of my computers is starting to fail. One of the internal batteries does not seem to be charging as it should. I guess it is time to replace the unit. I believe I purchased the UPS about 10 years ago. OK, I just ordered a replacement on Amazon. The UPS should arrive on Friday this week. Continue reading “Find Leaves of Binary Tree”

## Binary Tree Maximum Path

It is a Saturday morning in what has been forecasted so far as the coldest weekend of this winter season in the Twin Cities of Minneapolis and St. Paul. I woke up this morning around 05:00 AM and the temperature was at -8F. It seems like it will go up a few degrees during the day until it starts dropping down in the mid afternoon. On Sunday we should we waking up to a balmy -20F. My wife and I did our grocery shopping for the week yesterday evening. We are not planning on leaving home this weekend.

Earlier today I read Cybersecurity: Is it Worse than We Think? authored by Chris Maurer, Kevin Kim, Dan J Kim, and Leon Allan Kappelman in the latest Communications of the ACM magazine. The article is interesting, but there was a sentence that called my attention the most. The sentence follows:

“While they [organizations] may be saying the right things in public to satisfy investors, underwriters, and customers, there is an apparent lack of urgency in promoting a truly resilient and secure organization”.

You need to read the article to fully understand the meaning. In my opinion addressing cyber threats requires an investment which has no obvious ROI. Given that the word on the street is that it is not if but when a company will be hacked, then by doing as little as possible and carrying insurance to cover the cost of a breach seems the best approach. Of course if you ask a customer whose PID has been published in the dark web, the sentiments might be quite different. Continue reading “Binary Tree Maximum Path”

## 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”

## 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”

## Maximum Depth of a Binary Tree

Good morning. Hope your day has started on the right note. A couple weeks ago, the extended weather forecast for the Twin Cities of Minneapolis and St. Paul had the high temperatures in the low 60’s and 70’s. This week we have experienced high temperatures in the mid 80’s. It seems that with the power of the cloud, large models that make use of AI, and tons of data, accuracy predicting the weather is still out of our reach.

I have a lifetime friend. Our friendship started in elementary school. Now with the COVID-19 (or Chinese flu) pandemic we connect using Skype on Friday at 07:00 AM. By 08:00 AM we both start or work day. Continue reading “Maximum Depth of a Binary Tree”