how to use hash

Assume that set a has n elements, Set B has m elements, and the two sets are taken from a certain space (universe ). 1.1. First, start with the most naive method. For elements in B, perform a one-on-one test to determine whether the intersection

Problem: Find the 10 most visited IP addresses in the log file Similar Variants include: 1,Search for the 10 most popular search terms in the search engine record; 2,Search for 10 words with the highest frequency in a large file; 3. Web ProxyIn the

We know that statistics directly determine the execution plan produced by the relational engine.ArticleTwo examples are demonstrated. 1,Impact of statistical information on connection modes 2,Impact of statistical information on data acquisition

Lanfeng blog: http://bluesfeng.javaeye.com Recently, I was called by Google. it feels good. good chat with the interviewer. finally, he gave me some experience in preparing for a Google interview. I will share my experience with you below:

1. Applicability of nested loop connections (nested loops)Two tables: An External table and an internal table. If the external input is very small and the internal input is very large and an index has been created in advance, nested loop join will

Miyu original, post Please note: Reprinted from __________ White House   Question address: Http://acm.hdu.edu.cn/showproblem.php? PID = 1, 2526 Description: Romantic mobile phone Time Limit: 3000/1000 MS (Java/others) memory limit: 32768/32

This articleArticleIt was written by several database experts of databasecolumn. It briefly introduces mapreduce and compares it with the modern database management system, and points out some shortcomings. This article is purely a learning

In the past decade, Oracle has become one of the world's most professional databases. For IT experts, it is to ensure that their company's productivity is improved by leveraging the powerful features of oracle. One of the most effective methods is

Requirement: n elements are used to retrieve k elements with a maximum size (small). Describe the concept and algorithm. Note: Each method has its applicability. For example, some methods are applicable when n is large. Method 1: Sort the elements

Yesterday, HR made an appointment with us today. When we were about two minutes ago, the phone rang. If the resume is incomplete, let me send it to you again. Send the email to her. A few minutes later, the phone rings. 010. I picked up Baidu and

Rob beries http://acm.hdu.edu.cn/showproblem.php? PID = 1, 2955A backpack. When you do this for the first time, use the probability as a backpack (enlarge 100000 times to an integer ): in this range, what's the most frustrating is to think of the

Returns an array with N numbers and finds two numbers in the array so that the sum of the two numbers is close to 0. Http://www.cnblogs.com/haolujun/archive/2012/10/12/2721874.html This article provides several algorithms, including brute-force

This article describes the concepts and operations of Partitioned Tables from the following aspects: 1. Concepts of tablespaces and Partitioned Tables2. Specific functions of table partitions3. Advantages and Disadvantages of table partitions4.

SQL Optimization Oracle SQL optimization is a complex topic, and even requires the entire book to introduce the nuances of Oracle SQL optimization. However, there are some basic rules that every Oracle DBA must follow. These rules can improve the

This is an online database http://www.dbonline.cn.       Oracle expert tuning secret   Preface　　 In the past decade, Oracle has become one of the world's most professional databases. For IT experts, it is to ensure that their company's productivity

Hashmap is a great utility of JDK. It maps various objects and implements fast access to the corresponding "key-value. I feel ashamed after the study. Hash is to hash the object's hashcode through the key, and then obtain the index value in the

For more details, see click to open the link. Here, I will only talk about my views. This is based on slots. I think it is very helpful to establish a good mathematical model in your mind. Each slot is defined as a node {key, flag, pre, next} You

Android code optimization tips and android code tips This article mainly introduces some optimization tips for small details. When these tips are used in a comprehensive manner, they still play a role in improving the performance of the entire App,

Redis configuration details, redis details Web programmer blog: http://blog.csdn.net/thinkercode If it is a professional DBA, many parameters will be added when the instance is started to make the system run very stably, so that a parameter may

Hdu 1029 Ignatius and the Princess IV, hduignatiusIgnatius and the Princess IVTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32767 K (Java/Others)Total Submission (s): 18626 Accepted Submission (s): 7532Problem Description "OK, you are