sorting

问题 Basically I have a List<Map<String,Object>> , and I want to sort it by the values of certain key in the map. The problem is that I do not know the type... This map can contain Strings, Integers, Doubles, Floats etc.... I would like to sort it: So far List<Map<String,Object>> data = getResults(); Collections.sort(data, (o1, o2) -> (String.valueOf(o2.get("Field1"))) .compareTo((String.valueOf(o1.get("Field1"))))); It is not a great Idea since numbers are not properly sorted.... How can I handle

问题 I cannot seem to sort a 2 dimensional c array with std::sort. I can however sort a one dimensional array. This is in a case where I am being handed a c array in a c++ program and am hoping to sort without copying it over to a std::array. Maybe there is some way to turn it into a std::array without copying it? That sounds doubtful to me as any std::array would then call a destructor on memory that it does not own. Sorting One dimensional c style array works just fine: int len = 5; auto one_dim

问题 I try to sort array data alphabetically but I think something is not OK. var items; // it's OK items = ['a', 'á']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["a", "á"] // it's OK, too items = ['an', 'án']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["an", "án"] // hmmm, it's not items = ['an', 'ál']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["ál", "an"] The Hungarian alphabet starts with a, á, b, c... Any

问题 I try to sort array data alphabetically but I think something is not OK. var items; // it's OK items = ['a', 'á']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["a", "á"] // it's OK, too items = ['an', 'án']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["an", "án"] // hmmm, it's not items = ['an', 'ál']; items.sort((a, b) => a.localeCompare(b, 'hu')); console.log(items); // ["ál", "an"] The Hungarian alphabet starts with a, á, b, c... Any

问题 I have an array of filenames and need to sort that array by the extensions of the filename. Is there an easy way to do this? 回答1: Arrays.sort(filenames, new Comparator<String>() { @Override public int compare(String s1, String s2) { // the +1 is to avoid including the '.' in the extension and to avoid exceptions // EDIT: // We first need to make sure that either both files or neither file // has an extension (otherwise we'll end up comparing the extension of one // to the start of the other,

问题 I have an array of filenames and need to sort that array by the extensions of the filename. Is there an easy way to do this? 回答1: Arrays.sort(filenames, new Comparator<String>() { @Override public int compare(String s1, String s2) { // the +1 is to avoid including the '.' in the extension and to avoid exceptions // EDIT: // We first need to make sure that either both files or neither file // has an extension (otherwise we'll end up comparing the extension of one // to the start of the other,

问题 I know how to generally manipulate and create a multidimensional array but I don't know all the utils and features that arrays have. I want to know is if I have a 2D array the size of [5][4] , can I print it where the first line is in order, second is in reverse, and the third is in order... and so on. For example: [1 2 3 4] //in order [8 7 6 5] //reverse [9 10 11 12] //in order [16 15 14 13] //reverse [17 18 19 20] //in order as my teacher stated "Define a two-dimensional array of size m × n

问题 Assume I have a dictionary: d = {3: 'three', 2: 'two', 1: 'one'} I want to rearrange the order of this dictionary so that the dictionary is: d = {1: 'one', 2: 'two', 3: 'three'} I was thinking something like the reverse() function for lists, but that did not work. Thanks in advance for your answers! 回答1: Since Python 3.8 and above, the items view is iterable in reverse, so you can just do: d = dict(reversed(d.items())) On 3.7 and 3.6, they hadn't gotten around to implementing __reversed__ on

问题 Assume I have a dictionary: d = {3: 'three', 2: 'two', 1: 'one'} I want to rearrange the order of this dictionary so that the dictionary is: d = {1: 'one', 2: 'two', 3: 'three'} I was thinking something like the reverse() function for lists, but that did not work. Thanks in advance for your answers! 回答1: Since Python 3.8 and above, the items view is iterable in reverse, so you can just do: d = dict(reversed(d.items())) On 3.7 and 3.6, they hadn't gotten around to implementing __reversed__ on

问题 Ok so this is not a homework question obviously, but here is the thing: The bubble sort algorithm is said to be O(n^2), Ω(n). However, if we plot its time complexity as a graph (average case), and try to lower bound it, a more accurate lower bound would be Ω(n^2). However contextually we see that Ω(n) is correct. So why does lower bounding the algorithm's runtime does not work? 回答1: I think you're mixing up concepts: Lower bound vs upper bound: Ω(f(n)) is a lower bound, and O(f(n)) is an