impl Solution {
    pub fn merge(mut intervals: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
        // Check if the input is empty
        if intervals.is_empty() {
            return vec![];
        }

        // Sort the intervals based on the start of each interval
        intervals.sort_by(|a, b| a[0].cmp(&b[0]));

        let mut merged: Vec<Vec<i32>> = Vec::new();

        for interval in intervals.iter() {
            // If merged is empty or the current interval does not overlap with the last one in merged
            if merged.is_empty() || merged.last().unwrap()[1] < interval[0] {
                merged.push(interval.clone());
            } else {
                // If there is an overlap, merge the current interval with the last one in merged
                let last = merged.last_mut().unwrap();
                last[1] = i32::max(last[1], interval[1]);
            }
        }

        merged
    }
}

impl Solution {
    pub fn merge(mut intervals: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
        // Check if the input is empty
        if intervals.is_empty() {
            return vec![];
        }

        // Convert the intervals to a Vec of tuples for easier manipulation
        let mut intervals: Vec<(i32, i32)> = intervals.into_iter().map(|v| (v[0], v[1])).collect();

        // Sort the intervals based on the start of each interval
        intervals.sort_by(|a, b| a.0.cmp(&b.0));

        let mut merged: Vec<(i32, i32)> = Vec::new();

        for interval in intervals.iter() {
            // If merged is empty or the current interval does not overlap with the last one in merged
            if merged.is_empty() || merged.last().unwrap().1 < interval.0 {
                merged.push(*interval);
            } else {
                // If there is an overlap, merge the current interval with the last one in merged
                let last = merged.last_mut().unwrap();
                last.1 = i32::max(last.1, interval.1);
            }
        }

        // Convert the merged intervals back to Vec<Vec<i32>>
        merged
            .into_iter()
            .map(|(start, end)| vec![start, end])
            .collect()
    }
}