DIY: Maximum Frequency Stack

Solve the interview question "Maximum Frequency Stack" in this lesson.

Problem statement

Design a stack-like data structure. We should be able to push elements to this data structure and pop elements with maximum frequency.

You have to implement the FreqStack class:

  • FreqStack declare a frequency stack
  • push(data) pushes an integer data onto the top of the stack
  • pop removes and returns the most frequent element in the stack

If there is a tie for the most frequent element, the most recently pushed element is removed and returned.

Note: If the stack is empty, return -1

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