Solidworks model mania 2000

While searching for resources to practice advanced Solidworks modeling technique, I came across Solidworks Model Mania. Next higher level peak spotted. I just climb up the challenge.

The model mania was apparently held every year since 2000 as collected in the Solidworks official blog. Models are not straightforward to design. Some of them seems to be re-used for professional level certification exam, so a good site to practice for it.

 

Today I finished the very first one (for year 2000). It took me ~30 minutes to finish. Was not a very difficult one to model for me. Except that I spent over 10 minutes to figure out the left-most port length. According to the solution video, the dimension is not given in the 2D drawing. See below for the missing information.

There are many different ways to design a 3D solid body. One nice thing about the official blog is that they provide authoritative solution. You can brush up your memory on functions used less frequently, and start thinking about the best approach for the specific model. In short, highly recommended. I will keep trying the other ones.

LeetCode - solved 200 medium level problems

Progress report #2: I solved 100 medium level problems of LeetCode on 3/8, next 50 on 4/15, and today finished 200th. 56 days for the last 50 problems. Slightly less than one problem per day. Worse than the previous 50, but this time the problems were harder (lower acceptance rate). Anyway I now have strong confidence of being able to solve most of easy to intermediate level coding problems on major computer science algorithms. One weak area though is Dynamic Programming, particularly on sub-sequences (subset of array, where you can pick any elements but maintaining the original order). Now that I hit a significant milestone of 200, I plan to switch gear to self-studying DP, using GeeksForGeeks list of hundreds of representative problems. But I will also keep solving medium level LeetCode problems.

LeetCode - solved 150 medium level problems

A progress report: I solved 100 medium level problems of LeetCode on 3/8, and today finished 150th. Took 38 days to clear the 50 problems. ~1.3 per day on the average. Not too bad. There were one or two problems that I couldn't figure out myself after a few days of attempt, so that I consulted official solution (I still don't fully understand them though). Purely my effort otherwise.

Project Euler #233 - 10 months on a problem

I posted an article about a Project Euler problem on which I spent 41 days for a record. It was about two months after I seriously started solving PE. Now that I have just past one year mark, I have a far outstanding record: 10 months on #233. In fact (I keep progress record in Gmail so I can precisely track) I spent ~8 months without significant progress, and spent a month on a logical progress with a lot of test & research, finally into an answer. Unfortunately it was incorrect. So I consulted Project Euler Forum (never before for this problem), which had intermediate test cases I could check my reasoning / code against. It turned out that my logic was built upon a fundamentally wrong assumption, which I could have easily confirmed with brute force code for simpler cases instead of pure reasoning. Anyway I had to re-build logic. The underlying rule was not hard to figure out if one started with concrete evidences obtained from simple brute force codes. From that point, it took me two more days to write almost new code to get a correct answer. When I hit the answer correct, the moment I waited for 10 months, I felt empty than thrilled. Maybe I was overly exhausted by this single problem. By the number of  attempts that didn't work. Nevertheless I have never thought of giving up. I rather am the more attracted by other problems of similar or higher difficulty ratings (#233 has only 70% difficulty). I only wish I have weeks and months of free time. So that I can work on these problems 24/7. As infinite persistence is always ready by my side.

LeetCode - solved 100 medium level problems

On 2018 Christmas I posted an article upon finishing all easy-level problems of LeetCode. I said I will keep solving medium level ones. I did, and today I solved 100 out of 496 (as of this writing; LeetCode hosts weekly contest and add the problems to the list afterwards). It's been about 73 days since 2018/12/25 in which I have solved 24, but I was away on vacation, and I spent late December + early January mostly on becoming Certified Solidworks Expert, so I solved additional 76 problems in about a month and a week. Two problems per day on the average.

I solved medium level problems in descending order of acceptance. Meaning that I started from the easiest problems to progressively harder ones. But medium was medium. Significantly more difficult than easy ones. Easy problems were mostly about the basics; straightforward questions with good understanding of key data structure & algorithm. Medium problems went one step further in, demanding application (not too hard though) of basic concepts. One has to think quite a bit to decipher the required logic, implementation is more complicated and prone to mistake, and the final codes are longer. Moreover, there are algorithm topics of commensurate difficulty such as dynamic programming / Disjoint set & union find / Bitwise manipulation / stack / etc. I had to learn and review them carefully, so I couldn't solve 10 problems a day like I did with easy ones. However, the harder the problems are, the greater the thrills of solving them. That is the ultimate, undeniable attraction intellectually challenging questions in math / physics / coding have to offer.

I keep most of the source codes I wrote and associated thought process in my Gmail account for convenient re-visiting in the future. So far I am the more and more fascinated by these coding problems. Will keep it up!

Project Euler - level 10

Project Euler (PE) is a popular online math and coding challenge site. Compared to other CS-style coding-oriented sites such as HackerRank or LeetCode, PE problems heavily involve mathematics like number theory and geometry. PE problems are 'hard' in the sense that finding the governing math equations is not the end of the game. It typically asks you to count the number of integer solutions of the equation, which involves additional layer of number theory skills. One can brute force count, but it will take millions of years. Anyway, lying at the intersection of math and coding and math with comparable proportion, this site was exactly for me.

I started solving PE problems back in April 2018 for Python coding practice. The problems were easy at the beginning. I could solve more than 10 problems a day. But the problems became progressively difficult to solve. Instead of being distracted, I was the more fascinated by the challenge. Soon I was completely captivated by thinking of the solutions literally all day long. I was solving the problems while driving, taking showers, in the bed, in the bathroom; essentially whenever I could. I even completely stopped listening to podcasts while commute driving just to solve PE problems.

In the mean time I ran into an interesting article in Quora, questioning 'who are the people who solve 200+ PE problems?'. It had responses from people who actually solved over 200 problems, one of whom was contacted by and worked in Google. What a stimulus. Another reply claimed solving 200 problems in 4 months. I set the same milestone as my goal.

In the end, I passed the finish line in 115 days, a bit short of 4 months (progress summarized in GitHub repository). Note that I wasn't as committed before I set my goal. There were a few days in which I haven't tried any problems. Therefore I must have spent significantly less than 115 days in reaching 200. Due to the increasing difficulty, I had to reduce sleep to spare more time on the problems. I am proud that I solved all 200 problems without discussing with anyone else nevertheless.

I kept solving PE problems since, although at much slower pace after 200. And just yesterday I reached level 10 by solving another 50 problems in about 6 months. Roughly 2 problems per week. Only 1153 people in the world reached level 10 in the last ~17 years, out of ~880k registered users. Definitely a token of achievement, for tenacity and persistence.

After solving 60~70 problems I started saving my Python code. Furthermore, after solving ~100 problems, I have recorded the entire thought process including key insights and the points where I was stuck or made mistakes, along with pictures of handwritten paper notes. I don't publicly share any of them in accordance with PE policy. Contact me personally if I can be of help.

I will keep moving forward. Let's see how far I can go.

Certified Solidworks Expert

About a month ago I posted an article on Certified Solidworks Professional (CSWP). There I wrote that my ultimate goal is obviously reaching the highest level. Last Sunday I achieved the goal: I became the 3692nd Certified Solidworks Expert (CSWE) in the world. For comparison, there are approximately 100,700 CSWP and 230,000 CSWA (Associate) worldwide.

Expert level has a massive set of pre-requisites. On top of the CSWP, one needs to clear four of five advanced topics: Sheet Metals / Weldments / Drawing Tools / Surfacing / Molds. In other words one has to master nearly all key frameworks of mechanical design Solidworks has to offer. Then you are qualified to take the expert level exam.

For the expert level exam you have a 4 hours time frame without break to solve 20 problems. All of them are assigned 10 points, unlike other exams with varying points depending on difficulty. 160 points (80%) is the minimum passing grade. There were two multiple-choice questions, in contrary to the guide info saying no MPC. Half of the questions were on topics already covered by CSWP / CSWPAs but were significantly more difficult and/or demanded deeper understanding as well as mastery.

Below is the brief summary of my progress from the very beginning -

2018/11/08 : CSWA passed

2018/11/12 : CSWP segment 1 failed, 2 & 3 passed

2018/11/25 : CSWP segment 1 passed (CSWP completed)

2018/12/26 : CSWPA-SM (advanced - sheet metal) passed

2019/01/01 : CSWPA-SU (advanced - surfacing) failed

2019/01/09 : CSWPA-WD (advanced - weldments) passed

2019/01/13 : CSWPA-DT (advanced - drawing tools) passed

2019/01/16 : CSWPA-SU (advanced - surfacing) passed

2019/01/20 : CSWE passed

Until the end of 2018 I was all by myself; I took the exams with my prior experience + Solidworks official tutorial + a bit of Google search for video lectures on topics required by each exam for which I was not familiar with. At the beginning of 2019, however, I came across a extremely helpful LinkedIn lecture series by Gabriel Corbett. His videos cover virtually all sketch / parts / assembly / drawing functionalities systematically one by one. More importantly, he provides certification lectures that specifically targets each exams. (He even mentions in his video that he was involved in building and beta-testing Solidworks exams!) He pinpoints a number of tricky details that are hard to learn from official materials, and that are critical in solving those problems. He does a great job by helping people pass the exams easier and quicker, but he also shares numerous tips and know-hows that are not related to the exams. I learned so much from him. His lectures definitely helped me pass professional level exams fast.

For expert exam, I practiced with a book titled Certified SOLIDWORKS Expert Preparation Materials by Paul Tran. This book is specifically written for expert exam preparation. A bit expensive thinking of its volume, but you will find that the book is worth the money since there are little resources about the expert exam. Solidworks does not offer any test exam for the expert level to keep it the most challenging, and there are only less than four thousands of CSWE in the world. Where else can you get a real peek into the exam? Dassault Systemes (Developer company of Solidworks) should not like this book which reveals most of the heavenly secrets. From test taker's perspective, on the other hand, this book is the only and the must. The author shows you pretty much of everything you will see in the actual exam.

During the last 2~3 months of Solidworks self-study, I found a few interesting 3D modeling challenge sites, such as Solidworks model mania. Although I stepped on the top of the podium now, I am still hungry for further challenges. I want to further practice building models involving surfacing techniques. Just for fun for now.

A tip : from my experience, the exams were not much different between the first and the second time. Try taking screen shots for review if you think you can't make it at the first attempt, like what I did every time.