Design a data structure that keeps track of the values in it and answers some queries regarding their frequencies.
Implement the FrequencyTracker class.
Examples
Example 1
Input
["FrequencyTracker", "add", "add", "hasFrequency"]
[[], [3], [3], [2]]
Output
[null, null, null, true]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.add(3); // The data structure now contains [3]
frequencyTracker.add(3); // The data structure now contains [3, 3]
frequencyTracker.hasFrequency(2); // Returns true, because 3 occurs twice
Example 2
Input
["FrequencyTracker", "add", "deleteOne", "hasFrequency"]
[[], [1], [1], [1]]
Output
[null, null, null, false]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.add(1); // The data structure now contains [1]
frequencyTracker.deleteOne(1); // The data structure becomes empty []
frequencyTracker.hasFrequency(1); // Returns false, because the data structure is empty
Example 3
Input
["FrequencyTracker", "hasFrequency", "add", "hasFrequency"]
[[], [2], [3], [1]]
Output
[null, false, null, true]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.hasFrequency(2); // Returns false, because the data structure is empty
frequencyTracker.add(3); // The data structure now contains [3]
frequencyTracker.hasFrequency(1); // Returns true, because 3 occurs once
Constraints
1 <= number <= 105
1 <= frequency <= 105
At most, 2 * 105 calls will be made to add, deleteOne, and hasFrequency in total.
2671. Frequency Tracker
Medium
30 Points
Hash Table
Design
Design a data structure that keeps track of the values in it and answers some queries regarding their frequencies.
Implement the FrequencyTracker class.
Examples
Example 1
Input
["FrequencyTracker", "add", "add", "hasFrequency"]
[[], [3], [3], [2]]
Output
[null, null, null, true]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.add(3); // The data structure now contains [3]
frequencyTracker.add(3); // The data structure now contains [3, 3]
frequencyTracker.hasFrequency(2); // Returns true, because 3 occurs twice
Example 2
Input
["FrequencyTracker", "add", "deleteOne", "hasFrequency"]
[[], [1], [1], [1]]
Output
[null, null, null, false]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.add(1); // The data structure now contains [1]
frequencyTracker.deleteOne(1); // The data structure becomes empty []
frequencyTracker.hasFrequency(1); // Returns false, because the data structure is empty
Example 3
Input
["FrequencyTracker", "hasFrequency", "add", "hasFrequency"]
[[], [2], [3], [1]]
Output
[null, false, null, true]
Explanation
FrequencyTracker frequencyTracker = new FrequencyTracker();
frequencyTracker.hasFrequency(2); // Returns false, because the data structure is empty
frequencyTracker.add(3); // The data structure now contains [3]
frequencyTracker.hasFrequency(1); // Returns true, because 3 occurs once
Constraints
1 <= number <= 105
1 <= frequency <= 105
At most, 2 * 105 calls will be made to add, deleteOne, and hasFrequency in total.