fn video_stitching(clips: Vec<Vec<i32>>, time: i32) -> i32 {
    let mut arr = clips.clone();
    arr.sort_by(|a, b|
        if a[0] == b[0] {
            b[1].cmp(&a[1])
        }
        else {
            a[0].cmp(&b[0])
        }
    );

    if arr[0][0] != 0 {
        return -1;
    }

    let mut current_index = 0;
    let mut current_time = arr[0][1];
    let mut count = 1;

    while current_time < time {
        let mut max: Option<&Vec<i32>> = None;
        let mut max_index: Option<usize> = None;

        for (index, slice) in arr.iter().enumerate() {
            if index <= current_index {
                continue;
            }

            if slice[0] > current_time {
                break;
            }

            if max.is_none() || slice[1] > max.unwrap()[1] {
                max = Some(slice);
                max_index = Some(index);
            }
        }

        if let (Some(slice), Some(index)) = (max, max_index) {
            current_time = slice[1];
            current_index = index;
            count += 1;
        }
        else {
            return -1;
        }
    }

    count
}

fn main() {
    println!("{}", video_stitching(vec![vec![0,1]], 1));
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_simple() {
        let clips = vec![vec![0,1], vec![1,3], vec![3,7]];
        assert_eq!(video_stitching(clips, 7), 3);
    }

    #[test]
    fn test_ex1() {
        let clips = vec![
            vec![0,2], vec![4,6], vec![8,10],
            vec![1,9], vec![1,5], vec![5,9],
        ];
        assert_eq!(video_stitching(clips, 10), 3);
    }

    #[test]
    fn test_ex2() {
        let clips = vec![vec![0,1], vec![1,2]];
        assert_eq!(video_stitching(clips, 5), -1);
    }

    #[test]
    fn test_ex3() {
        let clips = vec![
            vec![0,1], vec![6,8], vec![0,2], vec![5,6],
            vec![0,4], vec![0,3], vec![6,7], vec![1,3],
            vec![4,7], vec![1,4], vec![2,5], vec![2,6],
            vec![3,4], vec![4,5], vec![5,7], vec![6,9],
        ];
        assert_eq!(video_stitching(clips, 9), 3);
    }

    #[test]
    fn test_n48() {
        let clips = vec![
            vec![ 8,10], vec![17,39], vec![18,19], vec![ 8,16],
            vec![13,35], vec![33,39], vec![11,19], vec![18,35],
        ];
        assert_eq!(video_stitching(clips, 20), -1);
    }
}