1024. Video Stitching

https://leetcode.com/problems/video-stitching

Description

You are given a series of video clips from a sporting event that lasted time seconds. These video clips can be overlapping with each other and have varying lengths.

Each video clip is described by an array clips where clips[i] = [starti, endi] indicates that the ith clip started at starti and ended at endi.

We can cut these clips into segments freely.

• For example, a clip [0, 7] can be cut into segments [0, 1] + [1, 3] + [3, 7].

Return the minimum number of clips needed so that we can cut the clips into segments that cover the entire sporting event [0, time]. If the task is impossible, return -1.

Example 1:

**Input:** clips = [[0,2],[4,6],[8,10],[1,9],[1,5],[5,9]], time = 10
**Output:** 3
**Explanation:** 
We take the clips [0,2], [8,10], [1,9]; a total of 3 clips.
Then, we can reconstruct the sporting event as follows:
We cut [1,9] into segments [1,2] + [2,8] + [8,9].
Now we have segments [0,2] + [2,8] + [8,10] which cover the sporting event [0, 10].

Example 2:

**Input:** clips = [[0,1],[1,2]], time = 5
**Output:** -1
**Explanation:** We can't cover [0,5] with only [0,1] and [1,2].

Example 3:

**Input:** clips = [[0,1],[6,8],[0,2],[5,6],[0,4],[0,3],[6,7],[1,3],[4,7],[1,4],[2,5],[2,6],[3,4],[4,5],[5,7],[6,9]], time = 9
**Output:** 3
**Explanation:** We can take clips [0,4], [4,7], and [6,9].

Example 4:

**Input:** clips = [[0,4],[2,8]], time = 5
**Output:** 2
**Explanation:** Notice you can have extra video after the event ends.

Constraints:

• 1 <= clips.length <= 100

• 0 <= starti <= endi <= 100

• 1 <= time <= 100

ac