986. Interval List Intersections

You are given two lists of closed intervals, firstList and secondList, where firstList[i] = [starti, endi] and secondList[j] = [startj, endj]. Each list of intervals is pairwise disjoint and in sorted order.

Return the intersection of these two interval lists.

A closed interval [a, b] (with a < b) denotes the set of real numbers x with a <= x <= b.

The intersection of two closed intervals is a set of real numbers that are either empty or represented as a closed interval. For example, the intersection of [1, 3] and [2, 4] is [2, 3].

 

Example 1:

Input: firstList = [[0,2],[5,10],[13,23],[24,25]], secondList = [[1,5],[8,12],[15,24],[25,26]]
Output: [[1,2],[5,5],[8,10],[15,23],[24,24],[25,25]]

Example 2:

Input: firstList = [[1,3],[5,9]], secondList = []
Output: []

Example 3:

Input: firstList = [], secondList = [[4,8],[10,12]]
Output: []

Example 4:

Input: firstList = [[1,7]], secondList = [[3,10]]
Output: [[3,7]]

 

Constraints:

  • 0 <= firstList.length, secondList.length <= 1000
  • firstList.length + secondList.length >= 1
  • 0 <= starti < endi <= 109
  • endi < starti+1
  • 0 <= startj < endj <= 109
  • endj < startj+1

Rust Solution

struct Solution;

impl Solution {
    fn interval_intersection(a: Vec<Vec<i32>>, b: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
        let mut res: Vec<Vec<i32>> = vec![];
        let mut i: usize = 0;
        let mut j: usize = 0;
        let n = a.len();
        let m = b.len();
        while i < n && j < m {
            let al = a[i][0];
            let ar = a[i][1];
            let bl = b[j][0];
            let br = b[j][1];
            if ar < bl {
                i += 1;
                continue;
            }
            if br < al {
                j += 1;
                continue;
            }
            let l = i32::max(al, bl);
            let r = i32::min(ar, br);
            res.push(vec![l, r]);
            if ar < br {
                i += 1;
            } else {
                j += 1;
            }
        }
        res
    }
}

#[test]
fn test() {
    let a: Vec<Vec<i32>> = vec_vec_i32![[0, 2], [5, 10], [13, 23], [24, 25]];
    let b: Vec<Vec<i32>> = vec_vec_i32![[1, 5], [8, 12], [15, 24], [25, 26]];
    let res: Vec<Vec<i32>> = vec_vec_i32![[1, 2], [5, 5], [8, 10], [15, 23], [24, 24], [25, 25]];
    assert_eq!(Solution::interval_intersection(a, b), res);
}

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