3369. Design an Array Statistics Tracker

Design a data structure that keeps track of the values in it and answers some queries regarding their mean, median, and mode.

Implement the StatisticsTracker class.

• StatisticsTracker(): Initialize the StatisticsTracker object with an empty array.
• void addNumber(int number): Add number to the data structure.
• void removeFirstAddedNumber(): Remove the earliest added number from the data structure.
• int getMean(): Return the floored mean of the numbers in the data structure.
• int getMedian(): Return the median of the numbers in the data structure.
• int getMode(): Return the mode of the numbers in the data structure. If there are multiple modes, return the smallest one.

Note:

• The mean of an array is the sum of all the values divided by the number of values in the array.
• The median of an array is the middle element of the array when it is sorted in non-decreasing order. If there are two choices for a median, the larger of the two values is taken.
• The mode of an array is the element that appears most often in the array.

Example 1:

Example 2:

Constraints:

• 1 <= number <= 109
• At most, 105 calls will be made to addNumber, removeFirstAddedNumber, getMean, getMedian, and getMode in total.
• removeFirstAddedNumber, getMean, getMedian, and getMode will be called only if there is at least one element in the data structure.