data-structures

问题 In my textbook, the implementation of the vector push_back move implementation is: void push_back( Object && x ) { if( theSize == theCapacity ) reserve( 2 * theCapacity + 1 ); objects[ theSize++ ] = std::move( x ); } My understanding of std::move is that it basically static casts the item as an rvalue reference. So why on the last line did they have to use std::move( x ), when x was passed in already as an rvalue reference? 回答1: x is an rvalue reference, but the rule of thumb you must follow

问题 In my textbook, the implementation of the vector push_back move implementation is: void push_back( Object && x ) { if( theSize == theCapacity ) reserve( 2 * theCapacity + 1 ); objects[ theSize++ ] = std::move( x ); } My understanding of std::move is that it basically static casts the item as an rvalue reference. So why on the last line did they have to use std::move( x ), when x was passed in already as an rvalue reference? 回答1: x is an rvalue reference, but the rule of thumb you must follow

问题 In my textbook, the implementation of the vector push_back move implementation is: void push_back( Object && x ) { if( theSize == theCapacity ) reserve( 2 * theCapacity + 1 ); objects[ theSize++ ] = std::move( x ); } My understanding of std::move is that it basically static casts the item as an rvalue reference. So why on the last line did they have to use std::move( x ), when x was passed in already as an rvalue reference? 回答1: x is an rvalue reference, but the rule of thumb you must follow

问题 In my textbook, the implementation of the vector push_back move implementation is: void push_back( Object && x ) { if( theSize == theCapacity ) reserve( 2 * theCapacity + 1 ); objects[ theSize++ ] = std::move( x ); } My understanding of std::move is that it basically static casts the item as an rvalue reference. So why on the last line did they have to use std::move( x ), when x was passed in already as an rvalue reference? 回答1: x is an rvalue reference, but the rule of thumb you must follow

问题 I've embarked on a project that is proving considerably more complicated than I'd first imagined. I'm trying to plan a system that is based around boolean (true/false) questions and answers. Users on the system can answer any questions from a large set of boolean (true/false) questions and be presented with a list showing the most similar users (in order of similarity) based on their answers. I've Googled far and wide but still not come up with much, so I was hoping somebody could point me in

问题 I've embarked on a project that is proving considerably more complicated than I'd first imagined. I'm trying to plan a system that is based around boolean (true/false) questions and answers. Users on the system can answer any questions from a large set of boolean (true/false) questions and be presented with a list showing the most similar users (in order of similarity) based on their answers. I've Googled far and wide but still not come up with much, so I was hoping somebody could point me in

问题 Are there any available implementations of a Hashtable that provide thread safety with minimal locking in .NET? Or in another language that can be ported to .NET? We're looking for something in between using a BCL Dictionary<,> class with lock() and a distributed caching application like memcached or Velocity. The intended use is for a cache with thousands of readers reading out immutable values based on keys (either numbers or guids, we haven't decided which yet). There will be far less

问题 While looking for a container suitable for an application I'm building, I ran across documentation for unordered_set . Given that my application typically requires only insert and find functions, this class seems rather attractive. I'm slightly put off, however, by the fact that find is O(1) amortized, but O(n) worst case - I would be using the function frequently, and it could make or break my application. What causes the spike in complexity? Is the likelihood of running into an O(n) search

问题 I'm currently building an application where I need to iterate over a series of steps that do largely the same thing, save a very small amount of code (~15 lines). The number of steps will vary depending on how the project is configured, so it seems kind of silly for me to create a separate function for each potential instance. In JavaScript, I would do something like this: var switches = [true, true, false, true]; var holder = { 0: function() { /* do step0 */ } 1: function() { /* do step1 */

问题 It's showing the wrong answer. Can anybody please tell me which test case I am missing ? Without Adjacent Given an array arr[] of N positive integers. The task is to find a subsequence with maximum sum such that there should be no adjacent elements from the array in the subsequence. Input: First line of input contains number of testcases T. For each testcase, first line of input contains size of array N. Next line contains N elements of the array space seperated. Output: For each testcase,