Introduction
It is so surprising that I can solve the decode ways to apply dynamic programming techniques. The conversation is like this. The peer asked me if I can solve the problem since he was asked in one of mock interview and then he failed to solve the problem since the idea of two pointer technique is not working. He was told to solve it using dynamic programming.
Dynamic programming is so much fun and I can quickly solve the algorithm after 12 months continuous practice on the same algorithm over and over again, and also learn from each peer when they work on those algorithms. After I failed several times on constructing the dynamic programming lookup table in two dimension, I finally build a template for myself to follow.
Two most favorite dynamic programming algorithms are deletion distance and regular expression matching. Usually what I like to do is to construct a look up table, work on base case first, and then figure out recursive formula. Detail can also look up here.
Algorithm practice
Here is the transcript I worked on in mock interview with a peer together. It is such great experience to share with the peer. I believe that once I have practiced dynamic programming algorithm on mock interview platform last 12 months so many times, I just apply the technique and find that it is not hard to figure out anymore. Here is the link to look up my practice on Leetcode 10: regular expression match hard level algorithm, including the blogs I worked as an interviewer as well.
What I did is to work on test case 1238712, build up a dynamic programming lookup table. And then go through from the left to right and find the answer 6 for the test case 1238712.
We had discussion together over 20 minutes on this dynamic programming lookup table, after we carefully went over the detail, I was told that the result is correct. The peer also went over to build the table by himself after I demoed how to construct it step by step.
One fact is that the peer shared with me the solution first, but I did not have to read the code the peer shared with me at all. I just told him to build a lookup table, work on a simple test case first.
Teaching and learning is so much fun since the peer is very busy and short of time. He has to prepare two interviews for top 10 software companies in less than one month. I am glad to learn from his experience as well.
One algorithm a time.
My personal advice
The peer told me that he only did one round of mock interview, after he finished all 30 question he stopped. He does not build strength if he keeps working on new algorithm.
Compared to the peer one round mock interview experience, I have more than 6 rounds. But what I found out is that I work on the same 30 algorithm over and over again. Even though I have to work on those dynamic programming algorithms over and over again, I worked on Leetcode 10: regular expression matching more than 30 times with various peers, I also kind of picking up a lot of things through those practice, from recursive function to dynamic programming, various languages from ruby programming to C++, Java and C#.
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