1942. The Number of the Smallest Unoccupied Chair
Description
There is a party where n
friends numbered from 0
to n  1
are attending. There is an infinite number of chairs in this party that are numbered from 0
to infinity
. When a friend arrives at the party, they sit on the unoccupied chair with the smallest number.
 For example, if chairs
0
,1
, and5
are occupied when a friend comes, they will sit on chair number2
.
When a friend leaves the party, their chair becomes unoccupied at the moment they leave. If another friend arrives at that same moment, they can sit in that chair.
You are given a 0indexed 2D integer array times
where times[i] = [arrival_{i}, leaving_{i}]
, indicating the arrival and leaving times of the i^{th}
friend respectively, and an integer targetFriend
. All arrival times are distinct.
Return the chair number that the friend numbered targetFriend
will sit on.
Example 1:
Input: times = [[1,4],[2,3],[4,6]], targetFriend = 1 Output: 1 Explanation:  Friend 0 arrives at time 1 and sits on chair 0.  Friend 1 arrives at time 2 and sits on chair 1.  Friend 1 leaves at time 3 and chair 1 becomes empty.  Friend 0 leaves at time 4 and chair 0 becomes empty.  Friend 2 arrives at time 4 and sits on chair 0. Since friend 1 sat on chair 1, we return 1.
Example 2:
Input: times = [[3,10],[1,5],[2,6]], targetFriend = 0 Output: 2 Explanation:  Friend 1 arrives at time 1 and sits on chair 0.  Friend 2 arrives at time 2 and sits on chair 1.  Friend 0 arrives at time 3 and sits on chair 2.  Friend 1 leaves at time 5 and chair 0 becomes empty.  Friend 2 leaves at time 6 and chair 1 becomes empty.  Friend 0 leaves at time 10 and chair 2 becomes empty. Since friend 0 sat on chair 2, we return 2.
Constraints:
n == times.length
2 <= n <= 10^{4}
times[i].length == 2
1 <= arrival_{i} < leaving_{i} <= 10^{5}
0 <= targetFriend <= n  1
 Each
arrival_{i}
time is distinct.
Solutions
Solution 1





