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Badge and Company.md

The following coding problem requires Senior engineer level or up to finish two questions within 50 minutes.

We are working on a security system for a badged-access room in our company's building.

1. Given an ordered list of employees who used their badge to enter or exit the room, write a function that returns two collections: a. All employees who didn't use their badge while exiting the room – they recorded an enter without a matching exit. b. All employees who didn't use their badge while entering the room – they recorded an exit without a matching enter.

badge_records = [
  ["Martha",   "exit"],
  ["Paul",     "enter"],
  ["Martha",   "enter"],
  ["Martha",   "exit"],
  ["Jennifer", "enter"],
  ["Paul",     "enter"],
  ["Curtis",   "enter"],
  ["Paul",     "exit"],
  ["Martha",   "enter"],
  ["Martha",   "exit"],
  ["Jennifer", "exit"]
] 

Expected output: ["Paul", "Curtis"], ["Martha"]

2. We want to find employees who badged into our secured room unusually often. We have an unordered list of names and access times over a single day. Access times are given as three or four-digit numbers using 24-hour time, such as "800" or "2250". Write a function that finds anyone who badged into the room 3 or more times in a 1-hour period, and returns each time that they badged in during that period. (If there are multiple 1- hour periods where this was true, just return the first one.) Notice that "10:00" - "11:00" is considered to be within a one-hour period, while "22:51" - "23:52" is not considered to be within a one-hour period.

badge_records = [
  ["Paul", 1315],
  ["Jennifer", 1910],
  ["John", 830],
  ["Paul", 1355],
  ["John", 835],
  ["Paul", 1405],
  ["Paul", 1630],
  ["John", 855],
  ["John", 915],
  ["John", 930],
  ["Jennifer", 1335],
  ["Jennifer", 730],
  ["John", 1630],
]

Expected output: `{"John": [830, 835, 855, 915, 930], "Paul": [1315, 1355, 1405]}

Time: O(N) , Space: O(N) .