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机器学习之树模型 大纲 决策树和回归树模型：ID3， C4.5，CART AdaBoost框架 提升树：梯度提升树 决策树 决策树模型可以看做是if-else指令集合，通过对特征空间的划分来完成分类或者回归任务。以下图中的分类任务为例，假设数据集包含了： 三个类别：黄色、蓝色、绿色 两个维度的特征空 阅读全文
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Happy Number Write an algorithm to determine if a number n is "happy". A happy number is a number defined by the following process: Starting with any 阅读全文
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Bitwise AND of Numbers Range Given a range [m, n] where 0 ⇐ m ⇐ n ⇐ 2147483647, return the bitwise AND of all numbers in this range, inclusive. Exampl 阅读全文
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Number of Islands Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by 阅读全文
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Binary Tree Right Side View Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered 阅读全文
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House Robber You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constrain 阅读全文
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Number of 1 Bits Write a function that takes an unsigned integer and return the number of '1' bits it has (also known as the Hamming weight). Example 阅读全文
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在阅读论文Understanding Black-box Predictions via Influence Functions时，看见了一种计算逆矩阵$H^{-1}$的方法： 定义$H_j^{-1} = \sum_j (I-H)i$，有$\mathbb[H_j{-1}] = H{-1}(j\rig 阅读全文