Archives: 2020 | Tech Blog

2020

07

21

graph

图 Graph 图形题不一定需要建图如果需要建图，考虑边是否具有方向考虑节点到本身是否有边建图方式邻接矩阵 Adjacency matrix space: O(|V|^2) search: O(1) 邻接表 Adj

2020-07-21 algorithm

19

dp

动态规划 Dynamic Programming 检查能不能拆分成子问题，且是否会被求解多次四大要素：状态，初始化，状态转移方程，结果优化空间，规律交错的题目尝试声明两个变量来存（一维DP两种状态）优化时间主要看内层循环的

2020-07-19 algorithm

algorithm 算法 dynamic programming

19

combination permutation

Combination 如果需要返回的组合长度不一样，则需要在外层调用dfs时加循环注意去重 time: O(2^n) int[] nums; List<List<Integer>> res = new ArrayLis

2020-07-19 algorithm

algorithm 算法 combination permutation

19

hands on: 13 preprocess

Data APILoad data from disk. dataset = tf.data.Dataset.from_tensor_slices((df.values, target.values)) Just use the belo

2020-07-19 Deep Learning

DL

16

hands on: 04 loss

Linear RegressionThe normal equation. $w = (X^TX)^{-1}X^Ty$ from sklearn.linear_model import LinearRegression lin_reg

2020-07-16 Deep Learning

DL

16

hands on: 02 e2e ml

A piece of info fed to a ML system is called a signal. We want a high signal-to-noise ratio. A sequence of data process

2020-07-16 Deep Learning

DL ML

14

hands on: 17 autoencoder

Performing PCA with an Undercomplete Linear AutoencoderThe following code builds a simple linear autoencoder to perform

2020-07-14 Deep Learning

DL

13

mybatis

JDBC缺点：非对象，修改表需要重写api。没用连接池，操作数据库需要频繁的创建和关联链接修改sql的话需要重编译java，不利于系统维护使用PreparedStatement预编译对变量进行编号，序号不利于维护返回结果集需要硬编

2020-07-13 Framework

mybatis

06

23

hands on: 07 ensemble

A group of predictors is called an enselmble. Voting ClassifiersAggregate the predictions of each classifier and predic

2020-06-23 Deep Learning

DL

20

shell

BasicVariableConvention: all caps for system variables, lower case for user defined variables. echo $BASH echo $BASH_VE

2020-06-20 Programming

shell

20

github

Introgit: system for version controlgithub: website to upload your directory .md (markdown file): ## This is the header

2020-06-20 app

app github

20

string

字符串考虑使用HashMap进行计数掌握substring, indexOf, isLetterOrDigit等常见方法考虑转换成char[] 比较一定要使用equals 找符合条件子串，考虑滑动窗口法，关键在于找到合法起始点 KMP

2020-06-20 algorithm

algorithm 算法 string