## 1024. Video Stitching

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

Each video clip `clips[i]` is an interval: it starts at time `clips[i][0]` and ends at time `clips[i][1]`.  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, T]`).  If the task is impossible, return `-1`.

Example 1:

```Input: clips = [[0,2],[4,6],[8,10],[1,9],[1,5],[5,9]], T = 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]], T = 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]], T = 9
Output: 3
Explanation:
We can take clips [0,4], [4,7], and [6,9].
```

Example 4:

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

Constraints:

• `1 <= clips.length <= 100`
• `0 <= clips[i][0] <= clips[i][1] <= 100`
• `0 <= T <= 100`

## Rust Solution

``````struct Solution;

use std::cmp::Reverse;

impl Solution {
fn video_stitching(mut clips: Vec<Vec<i32>>, t: i32) -> i32 {
clips.sort_by_key(|v| (v[0], Reverse(v[1])));
let n = clips.len();
let mut res = 0;
let mut left = 0;
let mut right = 0;
for i in 0..n {
if clips[i][0] >= t {
break;
}
if clips[i][0] < left {
right = right.max(clips[i][1]);
} else if clips[i][0] <= right {
right = right.max(clips[i][1]);
left = right;
res += 1;
} else {
return -1;
}
}
if right < t {
-1
} else {
if left < t {
res + 1
} else {
res
}
}
}
}

#[test]
fn test() {
let clips = vec_vec_i32![[0, 2], [4, 6], [8, 10], [1, 9], [1, 5], [5, 9]];
let t = 10;
let res = 3;
assert_eq!(Solution::video_stitching(clips, t), res);
let clips = vec_vec_i32![[0, 1], [1, 2]];
let t = 5;
let res = -1;
assert_eq!(Solution::video_stitching(clips, t), res);
let clips = vec_vec_i32![
[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]
];
let t = 9;
let res = 3;
assert_eq!(Solution::video_stitching(clips, t), res);
let clips = vec_vec_i32![[0, 4], [2, 8]];
let t = 5;
let res = 2;
assert_eq!(Solution::video_stitching(clips, t), res);
let clips = vec_vec_i32![
[5, 7],
[1, 8],
[0, 0],
[2, 3],
[4, 5],
[0, 6],
[5, 10],
[7, 10]
];
let t = 5;
let res = 1;
assert_eq!(Solution::video_stitching(clips, t), res);
}
``````

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