Interview

百度

一面

面向对象三大特性

封装，继承，多态

二面

c++中多态

虚函数，模板静态多态，函数重载静态多态，函数指针

源清慧虹

一面

笔试

A[MxN] x[N] = b[M] 方程的解和M，N相对大小的关系。

At least one solution, if and only if

rank(A) = rank(A,b)

If there is at least one solution, the solution is unique if and only if

rank(A)=N=number of variables

If there is at least one solution, there are infinity number of solutions, if and only if

rank(A)<N=number of variables

所以

M == N，可能具有无解，唯一解， 无数解

M < N，可能具有无解，无数解

M > N，可能具有无解，唯一解，无数解

LR和SVM区别

核密度估计(kernel density estimator)

高斯混合模型

Test set, validation set区别

高斯混合模型

In statistics, kernel density estimation (KDE) is a non-parametric way to estimate the probability density function of a random variable

EM算法

In statistics, an expectation–maximization (EM) algorithm is an iterative method to find maximum likelihood or maximum a posteriori (MAP) estimates of parameters in statistical models, where the model depends on unobserved latent variables