# Leetcode#253. Meeting Rooms II

Given an array of meeting time intervals `intervals`

where `intervals[i] = [starti, endi]`

, return *the minimum number of conference rooms required*.

**Example 1:**

**Input:** intervals = [[0,30],[5,10],[15,20]]

**Output:** 2

**Example 2:**

**Input:** intervals = [[7,10],[2,4]]

**Output:** 1

**Constraints:**

`1 <= intervals.length <= 104`

`0 <= starti < endi <= 106`

class Solution:

def minMeetingRooms(self, intervals: List[List[int]]) -> int:

# If there are no meetings, we don't need any rooms.

if not intervals:

return 0num_rooms = 0# Separate out the start and the end timings and sort them individually.

start_timings = sorted(i[0] for i in intervals)

end_timings = sorted(i[1] for i in intervals)

L = len(intervals)# The two pointers in the algorithm: e_ptr and s_ptr.

end_pointer = 0

start_pointer = 0# Until all the meetings have been processed

while start_pointer < L:

# If there is a meeting that has ended by the time the meeting at `start_pointer` starts

print(start_timings[start_pointer],end_timings[end_pointer])

if start_timings[start_pointer] < end_timings[end_pointer]:

# Free up a room and increment the end_pointer.

num_rooms += 1

else:

end_pointer += 1start_pointer += 1return num_rooms