Written by  on May 20, 2019

Faiss是什么 Faiss是FAIR出品的一个用于向量k-NN搜索的计算库,其作用主要在保证高准确度的前提下大幅提升搜索速度,根据我们的实际测试,基于1600w 512维向量建库,然后在R100@1000 (即召回top 1000个,然后统计包含有多少个实际距离最近的top 100)= 87%的前提下单机15线程可以达到1000的qps,这个性能应该是可以满足大部分的推荐系统召回模块性能需求了。

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Codeforces #1113C

Written by  on February 22, 2019

1113C C. Sasha and a Bit of Relax 题意 给一个数组,然后求满足 的[l, r]子序列有多少个,其中表示异或计算。 思路 关键点在于如果满足条件的[l,r]存在,那么

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Written by  on February 3, 2019


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Written by  on November 1, 2018

梯度提升决策树(Gradient Boosting Decision Tree, GBDT)是一种基于提升决策树(Boosting Tree)的模型以分类回归决策树(Classification and Regression Tree, CART)作为基本分类器的模型。

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Written by  on October 28, 2018

Word2Vec算法是NLP领域一个里程碑式的工作,它可以通过训练把文本内容映射到一个K维的向量,这样就很方便继续在其他一些算法领域里面使用,比如推荐系统或者广告点击率预估等等。它是在2013年由当时还在Google工作的Tomas Mikolov发表,主要两篇论文是《Distributed Representations of Words and Phrases and their Compositionality》和《Efficient Estimation of Word Representations in Vector Space》.

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Logistic Regression

Written by  on October 6, 2018

逻辑斯谛回归因为其易于实现,可解释性强,已经成为了工业界应用最广泛的机器学习算法。这篇文章主要讨论的是二项逻辑斯谛回归 (binominal logistic regression),以下简称LR。

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Written by  on September 28, 2018

Money is not evil by itself. It’s just paper with perceived value to obtain other things we value in other ways. If not money – what is evil you may ask?

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Written by  on August 18, 2018


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Written by  on August 14, 2018

POJ3020 Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 10821 Accepted: 5324 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most striking reason why they got the job, is their discovery of a new, highly noise resistant, antenna. It is called 4DAir, and comes in four types. Each type can only transmit and receive signals in a direction aligned with a (slightly skewed) latitudinal and longitudinal grid, because of the interacting electromagnetic field of the earth. The four types correspond to antennas operating in the directions north, west, south, and east, respectively. Below is an example picture of places of interest, depicted by twelve small rings, and nine 4DAir antennas depicted by ellipses covering them.

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Written by  on August 14, 2018

POJ3041 Asteroids Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 26141 Accepted: 14134 Description Bessie wants to navigate her spaceship through a dangerous asteroid field in the shape of an N x N grid (1 <= N <= 500). The grid contains K asteroids (1 <= K <= 10,000), which are conveniently located at the lattice points of the grid.

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