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问题 Let's say I want to generate 20 random numbers on a 8 by 6 grid.(8 columns, 6 rows) . Based on the answer from here:Creating random numbers with no duplicates, I wrote my code like this: Random randomNumGenerator = new Random(); Set<Integer[][]> generated = new LinkedHashSet<Integer[][]>(); while (generated.size() < 20) { int randomRows = randomNumGenerator.nextInt(6); int randomColumns = randomNumGenerator.nextInt(8); generated.add(new Integer[][]{{randomRows,randomColumns}}); } In reality

问题 The book Understanding ECMAScript 6 states that Sets don’t have keys, however. The people behind the ECMAScript 6 standard could have made the callback function in the set version of forEach() accept two arguments, but that would have made it different from the other two. Instead, they found a way to keep the callback function the same and accept three arguments: each value in a set is considered to be the key and the value. As such, the frst and second argument are always the same in forEach

问题 The book Understanding ECMAScript 6 states that Sets don’t have keys, however. The people behind the ECMAScript 6 standard could have made the callback function in the set version of forEach() accept two arguments, but that would have made it different from the other two. Instead, they found a way to keep the callback function the same and accept three arguments: each value in a set is considered to be the key and the value. As such, the frst and second argument are always the same in forEach

问题 I know up to eight Bit fields are merged into one byte to save space, but what if I have a couple of Bit fields and an Enum or a Set field? Are they internally merged too? I'm asking because I'm going to have a lot of rows in my table and I want to avoid overhead as much as possible. 回答1: According to the reference, SET fields use one byte minimum so those are out for any kind of merging. Update: ENUM is out, too: They take at least one byte as well. Reference 来源： https://stackoverflow.com

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Could not allocate memory My following code runs fine: double weight [600] [800][3]; double mean [600] [800][3]; double sd [600] [800][3]; double u_diff [600] [800][3]; for ( int i = 0; i < 600; i ++ ) { for ( int j = 0; j < 800; j ++ ) { for ( int k=0; k < 3; m ++ ) { weight [i][j][k] = 0; mean[i][j][k] = 0; sd[i][j][k] = 6; } } } But when I change it into this form: int init = 6; int C = 3; for ( int i = 0; i

问题 This question already has answers here : Javascript search for an object key in a set (5 answers) Closed 10 months ago . if I need to find an object in a Set. The set does not contain a natural key to use as an index, so I can't use Map. There are several different types of predicates used to search the Set. It seems inefficient to do const items = Array.from( mySet ) const found = items.find( item => someTest( item ) ) Unless there's black magic in the optimiser, it seems like it will

问题 I am trying to implement A* algorithm (with visualization in Qt). I've got this method: result_path astar_algorithm::calculate(mapview* m_view) { map_view = m_view; auto closed_set = std::vector<std::shared_ptr<node>>(); auto start_node = std::make_shared<node>(_start); auto open_set = std::vector<std::shared_ptr<node>>{start_node}; std::map<node, node> came_from; std::shared_ptr<node> current; while (!open_set.empty()) { current = *std::min_element(open_set.begin(), open_set.end()); if (

问题 So I know that a set is supposed to be an unordered list. I am trying to do some coding of my own and ended up with a weird happening. My set will sometimes go in order from 1 - 100 (when using a larger number) and when I use a smaller number it will stay unordered. Why is that? #Steps: #1) Take a number value for total random numbers in 1-100 #2) Put those numbers into a set (which will remove duplicates) #3) Print that set and the total number of random numbers import random randomnums = 0

问题 In a very busy PHP script we have a call at the beginning to "Set names utf8" which is setting the character set in which mysql should interpret and send the data back from the server to the client. http://dev.mysql.com/doc/refman/5.0/en/charset-applications.html I want to get rid of it so I set default-character-set=utf8 In our server ini file. (see link above) The setting seems to be working since the relevant server parameters are : 'character_set_client', 'utf8' 'character_set_connection'

问题 This question already has answers here : user defined object equality for a set in harmony (es6) (2 answers) Closed 4 years ago . I want to create a set of value objects in JavaScript. The problem is that in JavaScript equality is based on identity. Hence, two different objects with the same value will be treated as unequal: var objects = new Set; objects.add({ a: 1 }); objects.add({ a: 1 }); alert(objects.size); // expected 1, actual 2 How do you work around this problem? 回答1: Use JSON