2015 年 3月随笔档案 - desperadox

[Leetcode]Swap Nodes in Pairs

摘要：Given a linked list, swap every two adjacent nodes and return its head.For example,Given1->2->3->4, you should return the list as2->1->4->3.Your algor... 阅读全文

posted @ 2015-03-17 22:46 desperadox 阅读(136) 评论(0) 推荐(0) 编辑

[Leetcode]Sort Colors

摘要：Given an array withnobjects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, wh... 阅读全文

posted @ 2015-03-17 22:44 desperadox 阅读(188) 评论(0) 推荐(0) 编辑

[Leetcode]Unique Paths

摘要：A robot is located at the top-left corner of amxngrid (marked 'Start' in the diagram below).The robot can only move either down or right at any point ... 阅读全文

posted @ 2015-03-17 22:41 desperadox 阅读(167) 评论(0) 推荐(0) 编辑

[Leetcode]Find Minimum in Rotated Sorted Array

摘要：Suppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e.,0 1 2 4 5 6 7might become4 5 6 7 0 1 2).Find the minimum element.You m... 阅读全文

posted @ 2015-03-17 22:40 desperadox 阅读(98) 评论(0) 推荐(0) 编辑

[Leetcode]Merge Two Sorted Lists

摘要：Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.一直没想出原址排序... 阅读全文

posted @ 2015-03-15 23:24 desperadox 阅读(113) 评论(0) 推荐(0) 编辑

[Leetcode]Convert Sorted Array to Binary Search Tree

摘要：Given an array where elements are sorted in ascending order, convert it to a height balanced BST.分治是比较好而且容易想到的思路。 1 class Solution { 2 public: 3 T... 阅读全文

posted @ 2015-03-15 23:07 desperadox 阅读(104) 评论(0) 推荐(0) 编辑

[Leetcode]Unique Paths

摘要：A robot is located at the top-left corner of amxngrid (marked 'Start' in the diagram below).The robot can only move either down or right at any point ... 阅读全文

posted @ 2015-03-15 22:44 desperadox 阅读(213) 评论(0) 推荐(0) 编辑

[Leetcode]Climbing Stairs

摘要：You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb... 阅读全文

posted @ 2015-03-15 22:10 desperadox 阅读(110) 评论(0) 推荐(0) 编辑

[Leetcode]Remove Duplicates from Sorted List

摘要：Given a sorted linked list, delete all duplicates such that each element appear onlyonce.简单题，注意逻辑顺序就好了。 1 class Solution { 2 public: 3 ListNode *d... 阅读全文

posted @ 2015-03-15 21:46 desperadox 阅读(110) 评论(0) 推荐(0) 编辑

[Leetcode]Majority Element

摘要：Given an array of sizen, find the majority element. The majority element is the element that appears more than⌊ n/2 ⌋times.You may assume that the arr... 阅读全文

posted @ 2015-03-15 20:48 desperadox 阅读(120) 评论(0) 推荐(0) 编辑

[Leetcode]Maximum Subarray

摘要：Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array[−2,1,−3,4,−1,2,1,... 阅读全文

posted @ 2015-03-15 00:29 desperadox 阅读(138) 评论(0) 推荐(0) 编辑

[Leetcode]Search Insert Position

摘要：Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in or... 阅读全文

posted @ 2015-03-15 00:23 desperadox 阅读(105) 评论(0) 推荐(0) 编辑

[Leetcode]Binary Tree Inorder Traversal

摘要：Given a binary tree, return theinordertraversal of its nodes' values.和preorder是一样的，把左子节点一直压入到栈中，直到没有左子节点为止，然后出栈访问，存储右子节点。 1 vector inorderTraversal(Tr... 阅读全文

posted @ 2015-03-15 00:08 desperadox 阅读(117) 评论(0) 推荐(0) 编辑

[Leetcode]Populating Next Right Pointers in Each Node

摘要：Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set toNULL.Initially, all next ... 阅读全文

posted @ 2015-03-14 23:39 desperadox 阅读(139) 评论(0) 推荐(0) 编辑

[Leetcode]Binary Tree Preorder Traversal

摘要：Given a binary tree, return thepreordertraversal of its nodes' values.简单题，递归和迭代都可以解。 1 class Solution { 2 public: 3 vector preorderTraversal(TreeN... 阅读全文

posted @ 2015-03-14 23:18 desperadox 阅读(116) 评论(0) 推荐(0) 编辑

[机器学习]Generalized Linear Model

摘要：最近一直在回顾linear regression model和logistic regression model，但对其中的一些问题都很疑惑不解，知道我看到广义线性模型即Generalized Linear Model后才恍然大悟原来这些模型是这样推导的，在这里与诸位分享一下，具体更多细节可以参... 阅读全文

posted @ 2015-03-13 22:51 desperadox 阅读(3276) 评论(0) 推荐(0) 编辑

[Leetcode]Linked List Cycle

摘要：Given a linked list, determine if it has a cycle in it.简单题，只要知道快慢指针这个技巧就很容易解了。 1 class Solution { 2 public: 3 bool hasCycle(ListNode *head) { 4 ... 阅读全文

posted @ 2015-03-12 23:51 desperadox 阅读(138) 评论(0) 推荐(0) 编辑

[Leetcode]Excel Sheet Column Number

摘要：Given a column title as appear in an Excel sheet, return its corresponding column number.本质上是一个进制转换问题。1 class Solution {2 public:3 int titleToNumb... 阅读全文

posted @ 2015-03-12 23:45 desperadox 阅读(99) 评论(0) 推荐(0) 编辑

[Leetcode]Unique Binary Search Trees

摘要：Givenn, how many structurally uniqueBST's(binary search trees) that store values 1...n?简单动态规划。判别每个左右子树各有多少种情况，然后相乘就可以了，而且是BST，注意这条件就可以解了。它的状态转移方程为： ... 阅读全文

posted @ 2015-03-12 23:28 desperadox 阅读(94) 评论(0) 推荐(0) 编辑

[Leetcode]Same Tree

摘要：Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical an... 阅读全文

posted @ 2015-03-12 22:24 desperadox 阅读(98) 评论(0) 推荐(0) 编辑

[Leetcode]Maximum Depth of Binary Tree

摘要：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 le... 阅读全文

posted @ 2015-03-12 22:17 desperadox 阅读(98) 评论(0) 推荐(0) 编辑

[Leetcode]Single Number && Single Number II

摘要：Given an array of integers, every element appearstwiceexcept for one. Find that single one.非常简单的一道题。直接相异或剩下的那个数就是答案。原理是两个相等的数异或的值为0。1 class Solution {... 阅读全文

posted @ 2015-03-12 22:12 desperadox 阅读(172) 评论(0) 推荐(0) 编辑

[机器学习]决策树

摘要：决策树是简单的，易懂的，易实现的，同样也是强大的。决策树本身是一连串的if-else的组合，其最关键的问题就是对于一个输入数据集我们应该怎么去寻找这个if-else规则。按照先贤们的分法主要有如下几种：ID3,C4.5,CART。本文也将介绍这三种决策树。一、ID3 要想弄明白ID3决... 阅读全文

posted @ 2015-03-11 22:12 desperadox 阅读(1035) 评论(0) 推荐(0) 编辑

[机器学习]Bagging and Boosting

摘要：Bagging 和 Boosting 都是一种将几个弱分类器（可以理解为分类或者回归能力不好的分类器）按照一定规则组合在一起从而变成一个强分类器。但二者的组合方式有所区别。一、Bagging Bagging的思想很简单，我选取一堆弱分类器用于分类，然后最终结果投票决定，哪个票数多就属于哪一... 阅读全文

posted @ 2015-03-11 09:55 desperadox 阅读(766) 评论(0) 推荐(0) 编辑

[机器学习]SVM原理

摘要：SVM是机器学习中神一般的存在，虽然自深度学习以来有被拉下神坛的趋势，但不得不说SVM在这个领域有着举足轻重的地位。本文从Hard SVM 到 Dual Hard SVM再引进Kernel Trick，然后推广到常用的Soft Kernel SVM。一、Hard SVM SVM本身是从感知... 阅读全文

posted @ 2015-03-10 23:39 desperadox 阅读(2180) 评论(2) 推荐(2) 编辑

[算法]排序算法综述

摘要：排序算法有很多种，本文主要介绍基本的排序算法和实现，并分析复杂度和稳定性。一、Ο(n2)的算法 1、插入排序插入排序十分好理解，在无序的数组中选择一个数值，插入到有序的数组当中，这个过程是稳定的。实现代码如下： 1 template 2 void InsertionSort(vector &... 阅读全文

posted @ 2015-03-10 20:21 desperadox 阅读(208) 评论(0) 推荐(0) 编辑

03 2015 档案

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