1094. Car Pooling

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You are driving a vehicle that has capacity empty seats initially available for passengers.  The vehicle only drives east (ie. it cannot turn around and drive west.)
Given a list of trips, trip[i] = [num_passengers, start_location, end_location] contains information about the i-th trip: the number of passengers that must be picked up, and the locations to pick them up and drop them off.  The locations are given as the number of kilometers due east from your vehicle's initial location.
Return true if and only if it is possible to pick up and drop off all passengers for all the given trips. 

Example 1:
Input: trips = [[2,1,5],[3,3,7]], capacity = 4
Output: false
Example 2:
Input: trips = [[2,1,5],[3,3,7]], capacity = 5
Output: true
Example 3:
Input: trips = [[2,1,5],[3,5,7]], capacity = 3
Output: true
Example 4:
Input: trips = [[3,2,7],[3,7,9],[8,3,9]], capacity = 11
Output: true
 

Constraints:
  1. trips.length <= 1000
  2. trips[i].length == 3
  3. 1 <= trips[i][0] <= 100
  4. 0 <= trips[i][1] < trips[i][2] <= 1000
  5. 1 <= capacity <= 100000
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Intuition

At any trip, we add x number of people at location1, and drop them at location2
Car occupancy increases when people are picked, and decreases when dropped

We can process pick, and drop events left to right (sorted) and keep checking if capacity is excdeed after picking up people

If pick and drop location are same for different trips, we drop people first, and then pickup
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Time - O(n log n) - sorting
Space - O(n)
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