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》.
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.
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.