Valid Anagram
This one is a classic: `sorted(a) == sorted(b)`
Group Anagrams
Using product of prime numbers to create a key for anagrams is much faster than
sorting the characters in each word. It is also satisfyingly simple.
Encode and Decode Strings
My initial implementation was clumsy and prone to fail for edge-cases. A more
elegant solution is using something like:
```python
def encode(words):
return "".join("{}:{}".format(len(x), x) for x in words)
```
This is tricky because Python has variable-width integers, so relying on two's
complement to support the sum of negative numbers results in infinite
recursion. I know three ways to combat this:
1. Use Java.
2. Conditionally branch and handle either addition or subtraction accordingly.
3. Use a mask to enforce fixed-width integers in Python.
Looks like "Rotate Image" is the only Matrix problem that remains. It was nice
to learn more about "Backtracking" -- a term I often encounter -- while
attempting to solve "Word Search".
From my current understanding, it is like Brute Force but with
short-circuiting. It also seems quite similar to Depth First Search, and I'm
currently unaware of how DFS and Backtracking differ. I'm hoping to learn more
though.
I did these during my flight from LON->NYC without wifi. I managed to get both
correct on the first attempt although I did not find the *optimal* solution for
"Reorder List". IMO "Reorder List" is the best Linked List question I've seen
because it covers a few essential Linked List tricks.
Looks like I should prioritize the following topics:
- Dynamic Programming
- String
- Graph
Although I'm not sure how common DP questions are in interviews, DP is a useful
dragon to slay IMO.
TeamBlind.com hosts a curated list of DS&As questions from LeetCode.com that the
author claims appropriately samples the topics worth exploring. I'm creating an
offline list so that I can track my progress and work while I'm traveling.
