1288. Remove Covered Intervals

Given a list of intervals, remove all intervals that are covered by another interval in the list.

Interval [a,b) is covered by interval [c,d) if and only if c <= a and b <= d.

After doing so, return the number of remaining intervals.

 

Example 1:

Input: intervals = [[1,4],[3,6],[2,8]]
Output: 2
Explanation: Interval [3,6] is covered by [2,8], therefore it is removed.

Example 2:

Input: intervals = [[1,4],[2,3]]
Output: 1

Example 3:

Input: intervals = [[0,10],[5,12]]
Output: 2

Example 4:

Input: intervals = [[3,10],[4,10],[5,11]]
Output: 2

Example 5:

Input: intervals = [[1,2],[1,4],[3,4]]
Output: 1

 

Constraints:

  • 1 <= intervals.length <= 1000
  • intervals[i].length == 2
  • 0 <= intervals[i][0] < intervals[i][1] <= 10^5
  • All the intervals are unique.

Rust Solution

struct Solution;
use std::cmp::Reverse;

impl Solution {
    fn remove_covered_intervals(mut intervals: Vec<Vec<i32>>) -> i32 {
        intervals.sort_by_key(|v| (v[0], Reverse(v[1])));
        let n = intervals.len();
        let mut r = -1;
        let mut res = 0;
        for i in 0..n {
            let interval = &intervals[i];
            if interval[1] <= r {
                continue;
            } else {
                r = interval[1];
                res += 1;
            }
        }
        res
    }
}

#[test]
fn test() {
    let intervals = vec_vec_i32![[1, 4], [3, 6], [2, 8]];
    let res = 2;
    assert_eq!(Solution::remove_covered_intervals(intervals), res);
}

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