Program to find in which interval how many tasks are worked on in Python

Suppose we have a list of intervals where each interval is like [start, end) and we also have a list of strings called types. Now for a given i, the intervals[i] shows the times someone worked on the job types[i] from [start, end). Two intervals of the same type never overlap or touch. So we have to find a sorted merged list where each item has [start, end, num_types], indicates from start to end, num_types number of tasks were being worked on.

So, if the input is like intervals = [ [0, 3], [5, 7], [0, 7] ] types = ["problem solving", "news","game play"], then the output will be [[0, 3, 2], [3, 5, 1],[5, 7, 2]], as we have these few types of work being done: Between [0, 3) "problem solving" and "game play", between [3, 5) "game play", and between [5, 7) "news" and "game play".

To solve this, we will follow these steps −

• ev := a new list

• for each interval start end pair (s, e) in intervals, do

  • insert (s, 1) at the end of ev

  • insert (e, −1) at the end of ev

• sort the list ev

• cnt := 0, last := −1

• ans := a new list

• for each time and increment parameter of events (t, inc) in ev, do

  • if t is not same as last and cnt is not same as 0, then

    • cnt := cnt + inc

  • last := t

• return ans

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def solve(self, intervals, jobs):
      ev = []
      for s, e in intervals:
         ev.append((s, 1))
         ev.append((e, −1))
      ev.sort()
      cnt = 0
      last = −1
      ans = []
      for t, inc in ev:
         if t != last and cnt != 0:
            ans.append([last, t, cnt])
         cnt += inc
         last = t
      return ans
ob = Solution()
intervals = [
   [0, 3],
   [5, 7],
   [0, 7]
]
types = ["problem solving", "news", "game play"]
print(ob.solve(intervals, types))

Input

[[0, 3],[5, 7],[0, 7]], ["problem solving", "news", "game play"]

Output

[[0, 3, 2], [3, 5, 1], [5, 7, 2]]