2019年03月的内容
112. Path Sum(路径求和)
给定一个二叉树和一个和，确定该树是否有一个根到叶的路径，以便将路径上的所有值相加等于给定的和。注意：叶是没有子节点的节点。举例:给定如下二叉树以及 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \7 2 1返回 ……
111. Minimum Depth of Binary Tree(二叉树最小深度)
Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.Note: A leaf is a……
110. Balanced Binary Tree(平衡树判断)
Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as:a binary tree in which the depth of the two subtrees of ever……
浅谈机器学习共线性问题
这两天组里有同事在做特征分析这块的工作的时候其实会涉及到特征共线性问题，所以趁这个机会也去理解一下这个概念，说实话以前也没太在意这个问题。先看下共线性的基本概念多重共线性（Multicollinearity）是指线性回归模型中的自变量之间由于存在高度相关关系而使模型的权重参数估计失真或难以估计准确的一种特性，多重是指一个自变量可能与多个其他自变量之间……
Convert Sorted Array to Binary Search Tree(有序列表转化为BST)
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.For this problem, a height-balanced binary tree is defined as a binary tree in ……
107. Binary Tree Level Order Traversal II(二叉树分层排序)
Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root).For example:Given bina……
104. Maximum Depth of Binary Tree(二叉树深度-DFS方法)
Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.Note: A leaf is a……
101. Symmetric Tree
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 ……
rbm受限波兹曼算法理解
本文主要是参考了http://blog.echen.me/2011/07/18/introduction-to-restricted-boltzmann-machines/ 这篇文章，这个文章从二分因子的角度去理解，真的是讲得清新脱俗。背景：假设你要求一群用户从 0-100 分来给一组电影打分。在经典的因子分析中，你可以尝试依据一组隐藏因子来解释每部电影及……
