Interval List Intersections
The problem involves two lists of closed intervals, firstList
and secondList
, where each interval is represented as [start, end]
. The intervals within a list are pairwise disjoint and sorted. The task is to find the intersection of these two interval lists.
Solution
To find the intersection, we’ll use two pointers, one for each list, and iterate through both lists simultaneously, comparing intervals from each list.


Explanation
i
andj
are pointers for the current interval infirstList
andsecondList
, respectively. We loop through both lists simultaneously until we reach the end of either list.
 We find the start and end of the intersection using
max
andmin
functions.  If an intersection exists, we add it to the result.
 We increment the pointer for the list whose current interval ends first.
 Finally, we return the result, which is a list of intersecting intervals.
This code efficiently computes the intersection of two lists of intervals and returns the result in the required format.