xiao囡囡-优快云博客

转载 gbdt介绍

转自：前言：决策树这种算法有着很多良好的特性，比如说训练时间复杂度较低，预测的过程比较快速，模型容易展示（容易将得到的决策树做成图片展示出来）等。但是同时，单决策树又有一些不好的地方，比如说容易over-fitting，虽然有一些方法，如剪枝可以减少这种情况，但是还是不够的。模型组合（比如说有Boosting，Bagging等）与决策树相关的算法比较多，这些算法最终的结

2014-07-17 22:23:22 1559

转载 GBDT（MART）迭代决策树入门教程 | 简介

在网上看到一篇对从代码层面理解gbdt比较好的文章，转载记录一下： GBDT(Gradient Boosting Decision Tree) 又叫 MART（Multiple Additive Regression Tree)，是一种迭代的决策树算法，该算法由多棵决策树组成，所有树的结论累加起来做最终答案。它在被提出之初就和SVM一起被认为是泛化能力（g

2014-07-14 09:34:02 1192

原创 leetcode -day31 Subsets I II

1、SubsetsGiven a set of distinct integers, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not contain duplicate subset

2014-06-18 17:17:44 1546

原创 leetcode -day30 Reverse Linked List II

1、Reverse Linked List II Reverse a linked list from position m to n. Do it in-place and in one-pass.For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4,return 1->4->3->2->5->NULL.

2014-06-16 21:24:07 1299

原创 leetcode -day29 Binary Tree Inorder Traversal & Restore IP Addresses

1、Binary Tree Inorder TraversalGiven a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return

2014-06-14 09:23:19 1242

原创 leetcode -day28 Unique Binary Search Trees I II

1、Unique Binary Search Trees IIGiven n, generate all structurally unique BST's (binary search trees) that store values 1...n.For example,Given n = 3, your program should return all 5 uni

2014-06-13 09:22:53 1058

原创 leetcode -day27 Recover Binary Search Tree & Interleaving String

1、Recover Binary Search TreeTwo elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution using O(n) space is pretty

2014-06-04 10:17:42 1250

原创 leetcode -day26 Validate Binary Search Tree

1、Validate Binary Search TreeGiven a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes

2014-06-03 15:52:46 1066

原创 leetcodey -day25 Binary Tree Level Order Traversal & Symmetric Tree & Same Tree

1、Binary Tree Level Order TraversalGiven a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree {3,9

2014-06-02 21:48:02 1229

原创 leetcode -day24 Maximum Depth of Binary Tree & Binary Tree Zigzag Level Order Traversal

1、Maximum Depth of Binary TreeGiven 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.clas

2014-05-30 17:39:10 1223

原创 leetcode -day23 Construct Binary Tree from Inorder and Postorder Traversal & Construct Binary Tree f

1、Construct Binary Tree from Inorder and Postorder TraversalGiven inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in

2014-05-29 17:00:58 1724

原创 leetcode -day22 Binary Tree Level Order Traversal II & Convert Sorted Array to Binary Search Tree

1、Binary Tree Level Order Traversal IIGiven 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 e

2014-05-26 09:27:31 1110

原创 leetcode -day21 Longest Substring Without Repeating Characters

1、Longest Substring Without Repeating CharactersGiven a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letter

2014-05-22 21:54:59 1077

原创 leetcode -day20 Add Two Numbers

1、Add Two Numbers You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two num

2014-05-20 22:03:02 1247

原创 leetcode -day19 Convert Sorted List to Binary Search Tree

1、Convert Sorted List to Binary Search Tree Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.分析：将一个升序排列的链表转换为平衡二叉搜索树，采用递归的方式，先找到链表

2014-05-19 13:22:03 1499

原创 leetcode -day18 Balanced Binary Tree

1、Balanced Binary TreeGiven 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 subt

2014-05-18 21:39:15 1222

原创面试题整理19 矩阵Z字形扫描

题目：矩阵Z字形扫描对于

2014-05-17 09:35:00 3446

原创 leetcode -day17 Path Sum I II & Flatten Binary Tree to Linked List & Minimum Depth of Binary Tree

1、Path SumGiven a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example:Given the below

2014-05-17 09:33:25 1290

原创 leetcode -day16 ZigZag Conversion

1、ZigZag ConversionThe string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibili

2014-05-16 09:58:26 1497

转载小白鼠与毒药解题过程分析

网上流传着一题淘宝面试题，原题如下：我们有很多瓶无色的液体，其中有一瓶是毒药，其它都是蒸馏水，实验的小白鼠喝了以后会在5分钟后死亡，而喝到蒸馏水的小白鼠则一切正常。现在有5只小白鼠，请问一下，我们用这五只小白鼠，5分钟的时间，能够检测多少瓶液体的成分（）。A：5， B：6， C：31， D：32。+1只小白鼠首先可以想象只有1只小白鼠的情况，毫无疑问，1只小白鼠五分钟只能判

2014-05-14 18:57:14 1156

原创 leetcode -day 15 Distinct Subsequences

1、Distinct Subsequences Given a string S and a string T, count the number of distinct subsequences of T in S.A subsequence of a string is a new string which is formed from the original str

2014-05-14 10:42:19 1161

原创 leetcode -day14 Populating Next Right Pointers in Each Node I II

1、Populating Next Right Pointers in Each NodeGiven a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate

2014-05-13 11:03:48 968

原创 leetcode -day13 Valid Palindrome & Triangle & Pascal's Triangle I II

1、Valid PalindromeGiven a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,"A man, a plan, a canal: Panama" is a palindrom

2014-05-12 10:59:50 1075

原创 leetcode --day12 Surrounded Regions & Sum Root to Leaf Numbers & Longest Consecutive Sequence

1、Surrounded RegionsGiven a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'.A region is captured by flipping all 'O's into 'X's in that surrounded region.For e

2014-05-11 17:08:26 1086

原创 leetcode -day11 Clone Graph & Palindrome Partitioning I II

1、Clone GraphClone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ's undirected graph serialization:Nodes are labeled uniquely.We use # as

2014-05-08 22:18:57 1134

原创 leetcode -day10 Word Ladder I II

1、Word LadderGiven two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that:Only one letter can be changed at a tim

2014-05-07 15:19:36 1227

原创 leetcode -day9 Candy & Gas Station & Binary Tree Maximum Path Sum

1、CandyThere are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requirements:Each child must h

2014-05-06 17:31:19 1074

原创 leetcode -day8 Copy List with Random Pointer & Single Number I II

五一中间断了几天，开始继续。。。1、Copy List with Random PointerA linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.Return a

2014-05-05 14:21:12 1102

原创 leetcode day7 -- Word Break I II

1、Word Break

2014-04-29 22:52:27 1255

原创 leetcode day6 -- String to Integer (atoi) && Best Time to Buy and Sell Stock I II III

1、String to Integer (atoi)Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yours

2014-04-28 15:28:07 1261

原创 leetcode day5 -- Reorder List && Linked List Cycle II

1、Reorder List Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.For example,Given {1,2

2014-04-28 10:01:59 873

原创 leetcode day4 -- Binary Tree Postorder（Preorder) Traversal && Edit Distance

1、Binary Tree Postorder Traversal Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3retu

2014-04-27 10:56:07 1140

原创 leetcode day3 -- LRU Cache

1、LRU Cache Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.get(key) - Get the value (will always be posi

2014-04-26 21:59:46 1051

原创 leetcode day2 -- Sort List && Insertion Sort List

1、Sort ListSort a linked list in O(n log n) time using constant space complexity.分析：对链表排序不是第一次见，但是这是对非排序链表，看复杂度O(nlgn)，想到归并、快排、堆排等，但是对于链表不能随机存取，快排不适合。想到用归并的方法来实现，可以通过两个指针遍历求中点，将链表分成两端，分别排序，再

2014-04-25 15:10:33 1054

原创 leetcode day1 -- Reverse Words in a String && Evaluate Reverse Polish Notation && Max Points on a Li

以前从来没做过什么oj，发现做oj和在本地写代码或者纸上写差别还是很大的，觉得今天开始刷oj,特此记录一下。1、Reverse Words in a StringGiven an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue

2014-04-24 10:26:02 1146

转载轻松搞定面试中的红黑树问题

2014-04-22 17:38:57 965

转载面试题整理18 根据上排给出十个数，在其下排填出对应的十个数

给你10分钟时间，根据上排给出十个数，在其下排填出对应的十个数要求下排每个数都是先前上排那十个数在下排出现的次数。上排的十个数如下：【0，1，2，3，4，5，6，7，8，9】

2014-04-19 14:30:20 990

转载精选30道Java笔试题解答

转自：http://www.cnblogs.com/lanxuezaipiao/p/3371224.html 精选30道Java笔试题解答都是一些非常非常基础的题，是我最近参加各大IT公司笔试后靠记忆记下来的，经过整理献给与我一样参加各大IT校园招聘的同学们，纯考Java基础功底，老手们就不用进来了，

2014-04-16 20:44:11 889

原创 Mysql事务处理问题

今天和同学讨论起数据库事务处理的问题，感觉讨论中明白了一些，有些知识看过了，但是没有实际使用还是不理解。事务处理就是将一系列操作当做一个原子操作，要么全部执行成功，如果执行失败则保留执行期的状态。通过提交和回滚机制来实现操作，如果全部执行成功通过提交执行commit结果就会记录到数据库中，如果执行失败通过回滚操作rollback将发生错误之前的所有错误消除，回退到原来状态。事务都应该具备A

2014-04-10 20:26:39 1482

原创 sublime ：[Decode error - output not utf-8]

点击运行出错提示：[Decode error - output not utf-8]这几天出现此问题有几种情况，在加了编码为utf-8时，通常是语法错误：(1)tab键和空格键混合选中一行，可以看到行前面空的是点还是线，如果发现既有线又有点，估计就是这问题了，导致缩进不一致解决方法：设置将tab键自动换为4个空格键点击 Preference -> Settings-Us

2014-04-08 22:47:01 1594