Package g0401_0500.s0432_all_oone_data_structure

Class AllOne

  • All Implemented Interfaces:
    
public final class AllOne

    432 - All O\`one Data Structure\.

    Hard

    Design a data structure to store the strings' count with the ability to return the strings with minimum and maximum counts.

    Implement the AllOne class:

    • AllOne() Initializes the object of the data structure.

    • inc(String key) Increments the count of the string key by 1. If key does not exist in the data structure, insert it with count 1.

    • dec(String key) Decrements the count of the string key by 1. If the count of key is 0 after the decrement, remove it from the data structure. It is guaranteed that key exists in the data structure before the decrement.

    • getMaxKey() Returns one of the keys with the maximal count. If no element exists, return an empty string "".

    • getMinKey() Returns one of the keys with the minimum count. If no element exists, return an empty string "".

    Example 1:

    Input

    ["AllOne", "inc", "inc", "getMaxKey", "getMinKey", "inc", "getMaxKey", "getMinKey"]
[ [], ["hello"], ["hello"], [], [], ["leet"], [], []]

    Output: null, null, null, "hello", "hello", null, "hello", "leet"

    Explanation:

    AllOne allOne = new AllOne();
allOne.inc("hello");
allOne.inc("hello");
allOne.getMaxKey(); // return "hello"
allOne.getMinKey(); // return "hello"
allOne.inc("leet");
allOne.getMaxKey(); // return "hello"
allOne.getMinKey(); // return "leet"

    Constraints:

    • 1 <= key.length <= 10

    • key consists of lowercase English letters.

    • It is guaranteed that for each call to dec, key is existing in the data structure.

    • At most <code>5 * 10<sup>4</sup></code> calls will be made to inc, dec, getMaxKey, and getMinKey.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      AllOne()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Unit inc(String key)
      final Unit dec(String key)
      final String getMaxKey()
      final String getMinKey()

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait