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1166. Design File System (Medium)

You are asked to design a file system which provides two functions:

  • createPath(path, value): Creates a new path and associates a value to it if possible and returns True. Returns False if the path already exists or its parent path doesn't exist.
  • get(path): Returns the value associated with a path or returns -1 if the path doesn't exist.

The format of a path is one or more concatenated strings of the form: / followed by one or more lowercase English letters. For example, /leetcode and /leetcode/problems are valid paths while an empty string and / are not.

Implement the two functions.

Please refer to the examples for clarifications.

 

Example 1:

Input: 
["FileSystem","createPath","get"]
[[],["/a",1],["/a"]]
Output: 
[null,true,1]
Explanation: 
FileSystem fileSystem = new FileSystem();

fileSystem.createPath("/a", 1); // return true
fileSystem.get("/a"); // return 1

Example 2:

Input: 
["FileSystem","createPath","createPath","get","createPath","get"]
[[],["/leet",1],["/leet/code",2],["/leet/code"],["/c/d",1],["/c"]]
Output: 
[null,true,true,2,false,-1]
Explanation: 
FileSystem fileSystem = new FileSystem();

fileSystem.createPath("/leet", 1); // return true
fileSystem.createPath("/leet/code", 2); // return true
fileSystem.get("/leet/code"); // return 2
fileSystem.createPath("/c/d", 1); // return false because the parent path "/c" doesn't exist.
fileSystem.get("/c"); // return -1 because this path doesn't exist.

 

Constraints:

  • The number of calls to the two functions is less than or equal to 10^4 in total.
  • 2 <= path.length <= 100
  • 1 <= value <= 10^9

NOTE: create method has been changed on August 29, 2019 to createPath. Please reset to default code definition to get new method signature.

Related Topics

[Design] [Trie] [Hash Table] [String]

Hints

Hint 1 What if you think of a tree hierarchy for the files?.
Hint 2 A path is a node in the tree.
Hint 3 Use a hash table to store the valid paths along with their values.