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subject Sparse vector Title screenshot:  thinking 60 point answer My first idea is to open a two-dimensional array, which is equivalent to opening a two-dimensional table with two rows and many columns (why do you say many co ...

1. Topic description and online test location 1.1 the input is the user name and its score. Since the score includes three parts: online, midterm and end of the period, the input data of the same user name may contain multiple entries; The calculation rule of the final score is: on the premise that the online score is no less than 200, if ...

PAT admission number consists of 4 parts: The first is the level, that is, T stands for the top level; A stands for class A; B stands for class B; The 2nd to 4th digits are the examination room number, ranging from 101 to 999; The 5th ~ 10th place is the examination date, with the format of year, month and day, accounting for 2 places in seque ...

Learn what What is a map? How to create a map? Determine whether the key exists? How to get the map length? How to traverse a map? How to delete key / value pairs? Is map a reference type or a value type? concept map is an unordered set of key / value pairs, which is called dictionary, associative array, hash table and so on in other langua ...

Double column set: key: value public class MapDDDDemo { public static void main(String[] args) { Map map = new HashMap<Integer,String>(); map.put(1,"Hello"); map.put(2,"world"); map.put(3,"hello"); System.out.println("map Length:"+map.size()); System.out.println("map Include key ...