LeetCode 160 Intersection of Two Linked Lists in Java

In this post I will be solving LeetCode 160 Intersection of Two Linked Lists using the Java programming language.

Given the heads of two singly linked-lists headA and headB, 
return the node at which the two lists intersect. 
If the two linked lists have no intersection at all, return null.

Custom Judge:

The inputs to the judge are given as follows (your program is not given these inputs):

o intersectVal - The value of the node where the intersection occurs.
  This is 0 if there is no intersected node.
o listA - The first linked list.
o listB - The second linked list.
o skipA - The number of nodes to skip ahead in listA (starting from the head) 
  to get to the intersected node.
o skipB - The number of nodes to skip ahead in listB (starting from the head) 
  to get to the intersected node.

The judge will then create the linked structure based on these inputs and pass the two heads, 
headA and headB to your program.
If you correctly return the intersected node,
then your solution will be accepted.


o The number of nodes of listA is in the m.
o The number of nodes of listB is in the n.
o 1 <= m, n <= 3 * 104
o 1 <= Node.val <= 105
o 0 <= skipA < m
o 0 <= skipB < n
o intersectVal is 0 if listA and listB do not intersect.
o intersectVal == listA[skipA] == listB[skipB] if listA and listB intersect.

Related Topics:

* Hash Table
o Linked List
* Two Pointers

Follow up:

* Could you write a solution that runs in O(m + n) time and use only O(1) memory?

If interested I suggest you get the current description from LeetCode before you start coding. Continue reading “LeetCode 160 Intersection of Two Linked Lists in Java”

Producer and Consumer – Part 2

Yesterday the temperature in the Twin Cities of Minneapolis and St. Paul reached 72F which is quite pleasant for this time of the year. Today we are expecting 42F for a high. That is a drop of 30F! At least the day is forecasted to be sunny.

I also received a message from Gleves48061@hotmail.com regarding my post Revenue Milestones in Java. Not sure what it was all about so I will not comment on it at this time. If I could get an updated comment, I will review and reply as needed. Thanks. Continue reading “Producer and Consumer – Part 2”

Producer and Consumer

Hope you are doing well. I fully understand that not all countries are moving quickly to vaccinate most their population against COVID-19. Hopefully the efforts have already started and will be completed soon. Here in the USA it seems that every state is moving at its own pace. That said, a large amount of people have received at least the first of two jabs. The youngest I know of is of age 21. The world needs to get as much of its population vaccinated as possible to achieve herd immunity. If this is not done the virus will continue to mutate and the threat of COVID-19 might remain for years or decades.

It seems that Israel is leading the vaccination process. As in many other countries, there are some people that do not wish to get vaccinated. The prime minister of Israel has made some clever, and for what I understand legal changes to motivate all their citizens and residents to get a COVID-19 vaccine.

In a nutshell the idea is that the good of the majority needs to prevail. People will not be forced to get a vaccine unless there are medical reasons. Besides that, the population needs to show a vaccine passport to work where there is human contact with others. If the person wishes to attend events and places where they could possibly transmit COVID-19, they need to have a COVID test in the previous 48 hours. The COVID tests used to be free but in the near future people will need to pay for a test. So if a person for without a real medical issue does to get the vaccine but wishes to mix and mingle with others, they will have to pay and get a COVID test every other day. I guess Israel will be one of the countries that will reach heard immunity in the very near future. In my humble opinion, we in the USA need to start thinking about each other and work for a common goal. Continue reading “Producer and Consumer”

A Simple API

I always like to spend some time reviewing and learning new stuff before starting a project or task. The amount of time depends on the urgency of the task. In this case I went over chapter 2 of RESTful Web APIs by Leonard Richardson and Mike Amundsen.

As I have mentioned several times, I like to research a think about the task, implement a Minimum Viable Product (MVP) and with the remaining time enhance the software until the scheduled time runs out. Based on my experience, this approach is welcomed by most customers and development teams. When I say research and think, depending on the level and type of the task (e.g., architecting, designing, implementing), such activities may take from an hour or so to several days or weeks. The time is greatly reduced when you constantly read and experiment and when the task is implementation (i.e., generating and testing code). Continue reading “A Simple API”