#2671

Frequency Tracker

expert · 1115 · lc medium +32 · 30.9% accepted · 345 likes · top 8%

Description

Design a FrequencyTracker data structure with three operations: add(number) inserts number; deleteOne(number) removes one occurrence of number if it exists; hasFrequency(frequency) returns true if any value currently occurs exactly frequency times.

Example 1:

Input

["FrequencyTracker", "add", "add", "hasFrequency"]

[[], [3], [3], [2]]

Output

[null, null, null, true]

Example 2:

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 3:

Input

["FrequencyTracker", "add", "deleteOne", "hasFrequency"]

[[], [1], [1], [1]]

Output

[null, null, null, false]

Example 4:

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 5:

Input

["FrequencyTracker", "hasFrequency", "add", "hasFrequency"]

[[], [2], [3], [1]]

Output

[null, false, null, true]

Example 6:

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

Code

class FrequencyTracker:

    def __init__(self):
        

    def add(self, number: int) -> None:
        

    def deleteOne(self, number: int) -> None:
        

    def hasFrequency(self, frequency: int) -> bool:
        


# Your FrequencyTracker object will be instantiated and called as such:
# obj = FrequencyTracker()
# obj.add(number)
# obj.deleteOne(number)
# param_3 = obj.hasFrequency(frequency)

class FrequencyTracker:

    def __init__(self):
        

    def add(self, number: int) -> None:
        

    def deleteOne(self, number: int) -> None:
        

    def hasFrequency(self, frequency: int) -> bool:
        


# Your FrequencyTracker object will be instantiated and called as such:
# obj = FrequencyTracker()
# obj.add(number)
# obj.deleteOne(number)
# param_3 = obj.hasFrequency(frequency)