Given an array of bird where every element represents a bird type id, determine the id’s of the most frequently and least frequently sighted type. If more than 1 type has been spotted that maximum amount, return the smallest of their ids & If more than 1 type has been spotted that minimum amount, return the smallest of their ids.

E.g.: - Input – [1,1,2,2,4,4,4,4,5] Output – [4, 5]
Input – [2,2,2,2,4,4,4,4,5] Output – [2, 5]
Input – [1,2,2,4,4,4,4,5] Output – [4, 1]

Assumptions: The problem given is about birds so I have safely assumed that the array will not contain any negative values.

The quick idea was to use two nested loops. The outer loop will iterate the element in the birdArr and the inner loop keeps the count of max and min frequency of the birds. Obviously, this approach is the brute-force or naive approach as the time complexity tradeoff is O(n^2).

The second idea which came to me is to use a Hashtable or a Map. In this approach, I created a Map and populated it with the elements as keys of the Map and every element's frequency as their corresponding values. I could also have taken an auxiliary array for the same and kept the count but this idea was not good as for large ids, the memory would be wasted a lot. When using this approach the time complexity is significantly reduced to O(n) along with space complexity as O(n) since we took an extra space for Map.

1. Create a Map object map.
2. Populate map with the array elements as keys and their respective frequencies as values.
3. To get the keys corresponding to the maximum and minimum occurrence,
   1. Find the key corresponding to maximum value as well as minimum value.
   2. In case of a tie between maximum or minimum value of birds spotted, to return the minimum value based on min key, run a loop on map which is spread[ES6] to an array and calculate the minKey(initialized to MaxInteger) among the maximum or minimum ties.
4. Return the result as an array of Minimum and maximum value.

Given a time in 12-hr AM/PM format, convert it to military time(24hr) and you also need to add 45 min and 45 seconds in the result and display the output.

Input - 12:01:00PM Output 12:46:45
Input - 12:01:00AM Output 00:46:45

As mentioned in the problem, the time will be given in 12-hr AM/PM format, so there is no need to apply input sanity check. However, for edge cases, I used a regex-based sanity check on the input.

1. Split the given string input in order to get hour and AM/PM modifier. However, the tricky part is we cannot take the modifier directly since it is attached with 12-hr time format.
2. So, I used the regex :[0-5]\d:[0-5]\d for the same.
   1. : - Matches the colon literally.
   2. [0-5]\d - Matches the digits in the range 0-5 followed by any digit since maximum minutes and seconds could only be between 00-59.
3. After getting the hour and modifier,
   1. Check if hour is equal to 12. If yes, convert it to 00.
   2. Check if modifier is PM. If yes, parse the string hour to integer and add 12 to it.
4. Append the 46:45 minute and second and return the result.

NOTE: Flowchart's pdf is available in data folder.