Meeting Scheduler

# Time:  O(n) ~ O(nlogn)
# Space: O(n)
 
import heapq
 
 
class Solution(object):
    def minAvailableDuration(self, slots1, slots2, duration):
        """
        :type slots1: List[List[int]]
        :type slots2: List[List[int]]
        :type duration: int
        :rtype: List[int]
        """
        min_heap = list(filter(lambda slot: slot[1] - slot[0] >= duration, slots1 + slots2))
        heapq.heapify(min_heap)  # Time: O(n)
        while len(min_heap) > 1:
            left = heapq.heappop(min_heap)  # Time: O(logn)
            right = min_heap[0]
            if left[1]-right[0] >= duration:
                return [right[0], right[0]+duration] 
        return []   
 
 
# Time:  O(nlogn)
# Space: O(n)
class Solution2(object):
    def minAvailableDuration(self, slots1, slots2, duration):
        """
        :type slots1: List[List[int]]
        :type slots2: List[List[int]]
        :type duration: int
        :rtype: List[int]
        """
        slots1.sort(key = lambda x: x[0])
        slots2.sort(key = lambda x: x[0])
        i, j = 0, 0
        while i < len(slots1) and j < len(slots2):
            left = max(slots1[i][0], slots2[j][0])
            right = min(slots1[i][1], slots2[j][1])
            if left+duration <= right:
                return [left, left+duration]
            if slots1[i][1] < slots2[j][1]:
                i += 1
            else:
                j += 1
        return []