Compare with Past Years

I spent 1581/10 on 1st tasks which is about 60 hours less than last year and 230 hours less than the year before last year. Though it is primarily due to my relocation to PA and then to CA …

The first time I get to know red black tree is quite a few years ago when I was reading CLRS' famous Introduction to Algorithms. But at that time their explaination of red black tree was very tedious and couter-intuitive. Perhaps that's because the original red black tree is not very neat by itself. But anyway, Sedgewick later discovered the …

Poetry, Algorithm, and KMP

Great algorithms are poetry of computation Francis Sullivan

Poetry always give us an enjoyable exprience if not a meaningful enlightenment to the true nature of life. But 10 years ago when I first read about KMP on CLRS' classic Introduction to Algorithms, what I went through was only confusion. Though the code was succinct like a …

I came across a paper called A Few Useful Things to Know about Machine Learning which summarized some black arts in machine learning.

1. Learning = Representation + Evaluation + Optimization
2. It's generalization that counts
3. Data alone is not enough (we also need knowledge)
4. Overfitting has many faces
5. Intuition fails in high dimensions
6. Theoretical guarantee are not what they seem
7. Feature engineering is the …

LeetCode 137 is to find the number which apprears exactly once in an array assuming other numbers always appear exactly three times. It's very easy to come up with a linear runtime algorithm by using hash table which takes O(n) space. A better approach is to modulo count the number of occurrences of 1 at every bit and compose …