You are given a 2D integer array intervals of n elements, where intervals[i] = [starti, endi] represents the closed interval from starti to endi.
Return the number of pairs of indices (i, j) such that 0 <= i < j < n and intervals[i] and intervals[j] intersect.
Two intervals intersect if they have at least one point in common, including when they only share an endpoint.
Example 1:
Input: intervals = [[1,2],[2,3],[3,4]]
Output: 2
Explanation:
There are 2 intersecting interval pairs:
[1, 2] and [2, 3] intersect at the point 2.[2, 3] and [3, 4] intersect at the point 3.Example 2:
Input: intervals = [[1,5],[2,4],[3,6]]
Output: 3
Explanation:
There are 3 intersecting interval pairs:
[1, 5] and [2, 4] is [2, 4].[1, 5] and [3, 6] is [3, 5].[2, 4] and [3, 6] is [3, 4].Example 3:
Input: intervals = [[1,2],[3,4],[5,6]]
Output: 0
Explanation:
There are no intersecting interval pairs. Hence, the answer is 0.
Constraints:
2 <= n == intervals.length <= 105intervals[i] = [starti, endi]0 <= starti <= endi <= 109Loading editor...
[[1,2],[2,3],[3,4]]