hashmap

问题 I'm struggling to efficiently store information in pairs: For instance I have two structs that represent (x,y) coords that i wish to calculate and store the distance between. Currently I am store all the values twice in a unordered_map<pair<Struct1*,Struct2*,double> My problem is that when searching I want the result <Struct1*,Struct2*> to turn up the same value as <Struct2*,Struct1*> that way I do not have to store information twice. I've thought about using a multimap but I think that std:

问题 I have a many-to-one mapping in java hashmap. I iterate through all the values by using java.util.HashMap.values() . Now if I want to delete a particular value and all the corresponding keys, then what should I do? Will just using java.util.HashMap.remove(Object key) with one of the keys suffice? 回答1: In this example you can remove the values from a map without iteration. Code // The test map final Map<String, String> map = new HashMap<String, String>(); map.put("Key1", "Value"); map.put(

问题 I am trying to sort a hashmap based on alphabetical value which itself is stored inside another Map. The structure looks like: Map<String, HashMap<String, String>> I want to sort this Map based on the value of the HashMap inside so all in all the full map will be sorted so as the HashMap based on the HashMap's value. -- UPDATE: For example if I have something like: Map: abc Value: HashMap[EN, a] Map: xyz Value: HashMap[DE, c] Map: pqr Value: HashMap[PL, b] then after sort it should be

问题 This is a code to fetch a value from a key in HashMap. Why does it need to loop on line 317 to fetch the value ? Should this not be an O(1) operation ? public V get(Object key) { 315 if (key == null) 316 return getForNullKey(); 317 int hash = hash(key.hashCode()); 318 for (Entry<K,V> e = table[indexFor(hash, table.length)]; 319 e != null; 320 e = e.next) { 321 Object k; 322 if (e.hash == hash && ((k = e.key) == key || key.equals(k))) 323 return e.value; 324 } 325 return null; 326 } 回答1: The

问题 I have 6 const strings (5 letters each) I get a stream of few words (out of these 6 words). I want to count how many occurrences were out of each word. How can I implement it in C ? I have tried: char searchEngineNames[6][5] = { "waze_", "faceb", "fours", "googl", "fueli", "yello" }; static void foo(const char* res_name, int success, void *context, char *last_modified) { if (success){ for (int i=0; i<6; i++) { char substringFiveChars[6]; strncpy(substringFiveChars, res_name, 5); char

问题 In a previous post Creating a ToolTip Managed bean I was able to create a manged bean to collect and display tooltip text with only a single lookup and store them in an Application Scope variable. This has worked great. I am on the rather steep part of the JAVA learning curve so please forgive me. I have another managed bean requirement to create a HashMap Application Scope but this time it needs to be of a type String, Object. The application is where I have a single 'master' database that

问题 I asked a previous question on SO searching for specific keys in multiple independent hashMap objects about how to implemen this, or if I should implement a specific new class for my key. Eventually, after further reading of the docs, and noting that HashMap does already implement an equals() and hashcode() method I decided I would be good to go with using a HashMap as a key in my code. I've come to testing, and I've build an object of the following type HashMap< HashMap, Object> it is in

问题 Output reaches flag2 but I can't see what is inside the HashMap. The code is: public class traffic_analysis { static HashMap<InetAddress,Integer> mp=new HashMap<InetAddress, Integer>(); static void SrcCnt(InetAddress src_ip) { InetAddress SourceIP = src_ip; System.out.println(SourceIP); if (mp.get(SourceIP) == null){ mp.put(SourceIP, 0); System.out.println("----MPIKE----"); }else { mp.put(SourceIP,mp.get(SourceIP)+1); System.out.println("----MPIKE XANA----"); } System.out.println(mp.toString(

问题 I have a file which contains lots of properties file line by line may be around 1000 and each properties file will be having around 5000 key-value pair. For eg:- Sample Example(abc.txt)- abc1.properties abc2.properties abc3.properties abc4.properties abc5.properties So I am opening this file and as it reads each line I am loading the properties file in loadProperties method. And storing key-value pair from that property in LinkedHashMap. public class Project { public static HashMap<String,

问题 I'm reading the book " Learn Python the Hard way " by Zed Shaw, and currently I'm learning about dictionaries. In one of the exercises he creates a hashmap.py module. def new(num_buckets=256): """Intializes a Map with a given number of buckets""" aMap = [] for i in range(0, num_buckets): aMap.append([]) return aMap This is the first function he creates. I still have no idea what he is doing i lost track a while ago, (He claims if you just keep copying and try to understand the code it will