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问题 Spent a solid hour trying to sort out why on earth this (coffeescript) $.ajax accepts: "application/json; charset=utf-8" did absolutely nothing to change the accepts header, while this $.ajax dataType: "json" properly sets the accepts header to application/json; charset=utf-8 Totally confused, am I missing something or is the accepts attrib a year-round April Fool's joke? 回答1: As always the documentation is your friend: accepts Default: depends on DataType The content type sent in the request

问题 I was tinkering around with Python's set and frozenset collection types. Initially, I assumed that frozenset would provide a better lookup performance than set , as its immutable and thus could exploit the structure of the stored items. However, this does not seem to be the case, regarding the following experiment: import random import time import sys def main(n): numbers = [] for _ in xrange(n): numbers.append(random.randint(0, sys.maxint)) set_ = set(numbers) frozenset_ = frozenset(set_)

问题 I have two arrays, $a and $b here, and need to check if they contain exactly the same elements (independently of the order). I am thinking of using if (sizeof($a)==sizeof($b) AND array_diff($a,$b)==array()) { } But I am new to PHP, so I wonder: Is there a better way? Since I need to use them as sets, maybe I should not use arrays at all but something else. 回答1: The accepted answer is was wrong. It will would fail on: https://3v4l.org/U8U5p $a = ['x' => 1, 'y' => 2]; $b = ['x' => 1, 'y' => 1];

问题 What is the fastest way to count the number of set bits (i.e. count the number of 1s) in an UInt32 without the use of a look up table? Is there a way to count in O(1) ? 回答1: Is a duplicate of: how-to-implement-bitcount-using-only-bitwise-operators or best-algorithm-to-count-the-number-of-set-bits-in-a-32-bit-integer And there are many solutions for that problem. The one I use is: int NumberOfSetBits(int i) { i = i - ((i >> 1) & 0x55555555); i = (i & 0x33333333) + ((i >> 2) & 0x33333333);

问题 I need to generate a complete set of variants based on a list of N attributes, while keeping the attribute name intact. var input = [ { 'colour' : ['red', 'green'] }, { 'material' : ['cotton', 'wool', 'silk'] }, { 'shape' : ['round', 'square', 'rectangle'] } ]; var expected = [ { 'colour': 'red', 'material': 'cotton', 'shape': 'round' }, { 'colour': 'red', 'material': 'cotton', 'shape': 'square' }, { 'colour': 'red', 'material': 'cotton', 'shape': 'rectangle' }, { 'colour': 'red', 'material':

问题 This question already has answers here : Is it possible in java make something like Comparator but for implementing custom equals() and hashCode() (7 answers) Closed 6 years ago . I was looking for something akin to the Java TreeSet's ability to receive a custom comparator at instantiation time, so I needed not to use the object's default equality (and hash code) criteria. The closest I could come up with was to wrap my objects in a private custom class, but that seems hacky :( This ends up

问题 I'm looking for a PHP (with MYSQL) nested sets class with all needed functions. For example: createLeftNode, createRightNode,createRootNode, createSubNode,deleteNode and moveTree . Not only 1 left, 1 right, 1 up and 1 down but also a part of a tree in a nother tree. Thanks! 回答1: Well nested sets are great if you are working with hierarchical data. It's much more complex to implement it only with php arrays especially if you want to save these information in a database. you could try this on.

问题 I'm trying to make it working for quite some time,but just can't seem to get it. I have object Tower built of Block's. I've already made it working using arrays, but I wanted to learn Set's. I'd like to get similar functionality to this: public class Tower { public Tower(){ } public Tower add(Block k1){ //(...) //if block already in tower, return "Block already in tower" } public Tower delete(Block k1){ //(...) //if block already dleted, show "No such block in tower" } } Someone gave me some

问题 In Ruby, how do you set a variable to a certain value if it is not already defined, and leave the current value if it is already defined? 回答1: While x ||= value is a way to say "if x contains a falsey value, including nil (which is implicit in this construct if x is not defined because it appears on the left hand side of the assignment), assign value to x", it does just that. It is roughly equivalent to the following. (However, x ||= value will not throw a NameError like this code may and it

问题 Suppose the following: >>> s = set([1, 2, 3]) How do I get a value (any value) out of s without doing s.pop() ? I want to leave the item in the set until I am sure I can remove it - something I can only be sure of after an asynchronous call to another host. Quick and dirty: >>> elem = s.pop() >>> s.add(elem) But do you know of a better way? Ideally in constant time. 回答1: Two options that don't require copying the whole set: for e in s: break # e is now an element from s Or... e = next(iter(s)