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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. class FileSystem {
  8.   Map<String, Integer> pathMap;
  9.   Map<String, Runnable> callbackMap;
  10.  
  11.   public FileSystem() {
  12.     this.pathMap = new HashMap<>();
  13.     this.callbackMap = new HashMap<>();
  14.     this.pathMap.put("", 0);
  15.   }
  16.  
  17.   public boolean create(String path, int value) {
  18.     if (pathMap.containsKey(path)) {
  19.       return false;
  20.     }
  21.  
  22.     int lastSlashIndex = path.lastIndexOf("/");
  23.     if (!pathMap.containsKey(path.substring(0, lastSlashIndex))) {
  24.       return false;
  25.     }
  26.  
  27.     pathMap.put(path, value);
  28.     return true;
  29.   }
  30.  
  31.   public boolean set(String path, int value) {
  32.     if (!pathMap.containsKey(path)) {
  33.       return false;
  34.     }
  35.  
  36.     pathMap.put(path, value);
  37.  
  38.     // Trigger callbacks
  39.     String curPath = path;
  40.     while (curPath.length() > 0) {
  41.       if (callbackMap.containsKey(curPath)) {
  42.         callbackMap.get(curPath).run();
  43.       }
  44.       int lastSlashIndex = path.lastIndexOf("/");
  45.       curPath = curPath.substring(0, lastSlashIndex);
  46.     }
  47.  
  48.     return true;
  49.   }
  50.  
  51.   public Integer get(String path) {
  52.     return pathMap.get(path);
  53.   }
  54.  
  55.   public boolean watch(String path, Runnable callback) {
  56.     if (!pathMap.containsKey(path)) {
  57.       return false;
  58.     }
  59.  
  60.     callbackMap.put(path, callback);
  61.     return true;
  62.   }
  63. }
  64.  
  65. public class Main {
  66.   public static void main(String[] args) {
  67.     FileSystem fs = new FileSystem();
  68.     System.out.println(fs.get("/a")); // null
  69.     System.out.println(fs.set("/a", 2)); // false
  70.     System.out.println(fs.create("/a", 1)); // true
  71.     System.out.println(fs.get("/a")); // 1
  72.     System.out.println(fs.create("/a/b", 2)); // true
  73.     System.out.println(fs.create("/b/c", 3)); // false
  74.     System.out.println(fs.watch("/a/b", new Runnable() {
  75.       @Override
  76.       public void run() {
  77.         System.out.println("callback on /a/b");
  78.         System.exit(0);
  79.       }
  80.     }));
  81.     System.out.println(fs.watch("/a", new Runnable() {
  82.       @Override
  83.       public void run() {
  84.         System.out.println("callback on /a");
  85.         System.exit(0);
  86.       }
  87.     }));
  88.     System.out.println(fs.set("/a/b", 10)); // trigger 2 callbacks and true
  89.   }
  90. }
Success #stdin #stdout 0.08s 2316288KB
comments (?)
stdin
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Standard input is empty
stdout
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null
false
true
1
true
false
true
true
callback on /a/b
https://ideone.com/bcsfun
language:
Java (12.0.1)
created:
5 years ago
visibility:
public

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