sorting

问题 Given n numbers, how do I find the largest and second largest number using at most n+log(n) comparisons? Note that it's not O(n+log(n)), but really n+log(n) comparisons. 回答1: pajton gave a comment. Let me elaborate. As pajton said, this can be done by tournament selection. Think of this as a knock out singles tennis tournament, where player abilities have a strict order and the outcome of a match is decided solely by that order. In the first round half the people are eliminated. In the next

问题 I have a class that implements IComparable. public class MyClass : IComparable<MyClass> { public int CompareTo(MyClass c) { return this.whatever.CompareTo(c.whatever); } etc.. } I then can call the sort method of a generic list of my class List<MyClass> c = new List<MyClass>(); //Add stuff, etc. c.Sort(); and have the list sorted according to my comparer. How do i specify further comparers to sort my collection different ways according to the other properties of MyClass in order to let users

问题 I have this multidimensional array: Array ( [0] => Array ( [0] => 2012-02-26 07:15:00 ) [1] => Array ( [0] => 2012-02-26 17:45:00 [1] => 2012-02-26 18:55:00 ) [2] => Array ( [0] => 2012-02-26 18:55:00 [1] => 2012-02-26 17:45:00 ) [3] => Array ( [0] => 2012-02-26 18:57:00 [1] => 2012-02-26 17:45:00 [2] => 2012-02-26 18:55:00 ) When I count subarrays I get this 1,2,2,3. How could I receive it in 3,2,2,1? I need to get for example last 3 subarrays with the highest subarray count (DESC, it means

问题 This question already has answers here : Sort dataframe by string length (2 answers) Closed 2 years ago . Using Python. I have a dataframe with three columns: Author | Title | Reviews I want to sort by the length of the string in the Reviews column. If I do df.sort_values('Review', ascending = False) It sorts alphabetically, starting with ' z '. How do I get it to sort by the length of the string in the Reviews column? 回答1: I think you need len for lengths assign to index, sort_index and last

问题 Please consider this List: "A", "C", "AB", "AD", "N", "Z", "AC" I want to sort this string (That are being Excel column) like Excel Column Sorting. I want the result like this: "A", "C", "N", "Z", "AB", "AC", "AD" Is it possible using LINQ OrderBy? What is the best approach? Thanks 回答1: Update : Thanks @JeppeStigNielsen for correct comment, I add StringComparer.Ordinal to support in all cultures: var result = List.OrderBy(p=>p.Length).ThenBy(p=>p,StringComparer.Ordinal); 回答2: First order by

问题 Today I found a strange for me implementation of strings sorting: ['Data', 'Chata', 'Clata'].sort(function(a, b) { return a > b}); Using this approach we take a valid sorted array as the output - ["Chata", "Clata", "Data"] . But I don't clearly understand why it works... I know that comparator function expects three different outputs - zero, integer above zero, integer below zero. But in this case we can take only two values - true (if a greater than b) or false (if a less than b) (1 or 0

问题 This question already has answers here : How can I sort arrays and data in PHP? (11 answers) Closed 5 years ago . I know there are some other topics about sorting with multiple criteria, but they don't fix my problem. Let's say I have this array: Array ( [0] => Array ( [uid] => 1 [score] => 9 [endgame] => 2 ) [1] => Array ( [uid] => 2 [score] => 4 [endgame] => 1 ) [2] => Array ( [uid] => 3 [score] => 4 [endgame] => 100 ) [3] => Array ( [uid] => 4 [score] => 4 [endgame] => 70 ) ) I want to

问题 Counting sort is known with linear time if we know that all elements in the array are upper bounded by a given number. If we take a general array, cant we just scan the array in linear time, to find the maximum value in the array and then to apply counting sort? 回答1: It is not enough to know the upper bound to run a counting sort: you need to have enough memory to fit all the counters. Consider a situation when you go through an array of 64-bit integers, and find out that the largest element

问题 I have 2 dictionaries, dict1 and dict2 which contain the same keys, but different values for the keys. What I want to do is for each dictionary, sort the values from largest to smallest, and then give each value a rank 1-N, 1 being the largest value. From here, I want to get the difference of the ranks for the values in each dictionary for the same key. For example: dict1 = {a:0.6, b:0.3, c:0.9, d:1.2, e:0.2} dict2 = {a:1.4, b:7.7, c:9.0, d:2.5, e:2.0} # sorting by values would look like this

问题 For example: int A[] = {3,2,1,2,3,2,1,3,1,2,3}; How to sort this array efficiently? This is for a job interview, I need just a pseudo-code. 回答1: Problem description: You have n buckets, each bucket contain one coin , the value of the coin can be 5 or 10 or 20. you have to sort the buckets under this limitation: 1. you can use this 2 functions only: SwitchBaskets (Basket1, Basket2) – switch 2 baskets GetCoinValue (Basket1) – return Coin Value in selected basket 2. you cant define array of size