DataStructureFundamentalJava, branch master UCSD Data Structures Fundamentals exercises done in Java https://www.edx.org/course/data-structures-fundamentals-uc-san-diegox-algs201x Solved, yay I'm happy. I had to put this aside for a couple of months 2019-12-02T03:11:57+00:00 Haidong Ji 2019-12-02T03:11:57+00:00 a2acdcaa02b85f7733d4b24c75583a502a1a9da4 due to busy work and family life. Yesterday and today I got a little time so I fired up IDEA and started hacking at this again. Lesson learned/reinforced: don't give up, don't dismiss small steps, take those steps like a marathon, and you'll inch closer and finally reach the destination! I found that it helped me that I wrote down those little steps, started them, finished them, and closed them one by one. This gave me momentum to carry it through! Pretty happy about it. 
due to busy work and family life. Yesterday and today I got a little
time so I fired up IDEA and started hacking at this again.

Lesson learned/reinforced: don't give up, don't dismiss small steps,
take those steps like a marathon, and you'll inch closer and finally
reach the destination! I found that it helped me that I wrote down
those little steps, started them, finished them, and closed them one
by one. This gave me momentum to carry it through! Pretty happy about
it.
Salvaged SetRangeSum from the grader and test checkin. The long story 2019-09-04T20:55:37+00:00 Haidong Ji 2019-09-04T20:55:37+00:00 50679f7f32fe06e1e1952dc073bcec10d284dec0 is that I rebuilt the machine from Manjaro to Deepin then back to Manjaro again. Unfortunately I lost the test file, which I'll recreate. 
is that I rebuilt the machine from Manjaro to Deepin then back to
Manjaro again. Unfortunately I lost the test file, which I'll recreate.
"is it binary search tree hard" done! 2019-06-13T01:06:47+00:00 Haidong Ji 2019-06-13T01:06:47+00:00 18ae1ea81ee05c62b325bf91813f7d293228df45 not too bad, just allowing the right node being equal or greater. Two modifications to the code was needed. 
not too bad, just allowing the right node being equal or greater. Two
modifications to the code was needed.
"is it binary search tree" done! 2019-06-12T03:21:50+00:00 Haidong Ji 2019-06-12T03:21:50+00:00 578980d5ff80f94c9748d806879b7b707eec441e This is not too bad. Since I got the tree traversal done in the last exercise, I just used the in-order traversal as a base and modified a bit. 
This is not too bad. Since I got the tree traversal done in the last
exercise, I just used the in-order traversal as a base and modified a
bit.
woohoo, tree order traversal done! 2019-06-09T16:54:36+00:00 Haidong Ji 2019-06-09T16:54:36+00:00 ad183107055509e73c7a0740c1dd633f212d0f51 Once again a lot of fun. I had about 3 months hiatus due to house purchasing, where I didn't touch this exercise, more or less. Today I made an effort following TDD and got the last post order traversal done! I worried if edx/course staff stopped the auto grader. It turned out they didn't. Really happy :) 
Once again a lot of fun. I had about 3 months hiatus due to house
purchasing, where I didn't touch this exercise, more or less. Today I
made an effort following TDD and got the last post order traversal done!
I worried if edx/course staff stopped the auto grader. It turned out
they didn't. Really happy :)
check in post-order test cases 2019-03-24T02:12:13+00:00 Haidong Ji 2019-03-24T02:12:13+00:00 bf7d8fa962098eeafc4eed84e4ae0450806a43c3 






In-order and pre-order binary tree traversal done
2019-03-22T23:02:48+00:00

Haidong Ji

2019-03-22T23:02:48+00:00

acff8424e09a3531cae111a93fb0f6fce1d4404e

I worked this out myself, using iterative approach instead of recursive
to avoid stack overflow issues. Post-order traversal not done yet. I'll
likely follow pseudo code from this wiki page to get that done:
https://en.wikipedia.org/wiki/Tree_traversal





I worked this out myself, using iterative approach instead of recursive
to avoid stack overflow issues. Post-order traversal not done yet. I'll
likely follow pseudo code from this wiki page to get that done:
https://en.wikipedia.org/wiki/Tree_traversal







Rabin-Karp string search done!
2019-03-17T02:52:16+00:00

Haidong Ji

2019-03-17T02:52:16+00:00

b1aea90f00a4bf65253946b9f1017b6c9804535a

Fun exercise. Some takeaways:
1. Smallest test case is easy to walk through and verify the logic,
indexing, and such is correct;
2. Persist, don't give up, take it step by step, and you'll reach the goal!

Hooray!





Fun exercise. Some takeaways:
1. Smallest test case is easy to walk through and verify the logic,
indexing, and such is correct;
2. Persist, don't give up, take it step by step, and you'll reach the goal!

Hooray!







Hash chain simulation done!
2019-03-11T03:15:07+00:00

Haidong Ji

2019-03-11T03:15:07+00:00

8fdeec331c424f2a7cfc98619e98a0d2420ddf7c

Created test cases for the hash function. Tested the code by running the
main function without writting test cases. I wish the starter code was
written in a way that facilitated testing...





Created test cases for the hash function. Tested the code by running the
main function without writting test cases. I wish the starter code was
written in a way that facilitated testing...







Phone book done!
2019-03-10T01:06:35+00:00

Haidong Ji

2019-03-10T01:06:35+00:00

8e0d78c1b52e84dfbdb2765d9c4183ab2116c2d1

I cheated and didn't modify the starter code so it's testable. It seems
that starter code in this course is not written as well as the first
course.





I cheated and didn't modify the starter code so it's testable. It seems
that starter code in this course is not written as well as the first
course.