Introduction

In this blog post, we will explore how to solve the LeetCode problem "986" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

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: [] 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

Explanation

Here's the breakdown of the solution:

• Iterate and Compare: Use two pointers, one for each list, and iterate through them simultaneously. At each step, compare the current intervals from both lists.
• Calculate Intersection: If the intervals overlap, calculate their intersection by taking the maximum of the start points and the minimum of the end points.

• Advance Pointer: Advance the pointer of the interval that ends earlier, as it cannot intersect with any further intervals in the other list until that list advances past its end point.

• Runtime Complexity: O(m+n), where m and n are the lengths of the input lists.

• Storage Complexity: O(k), where k is the number of intersecting intervals in the result.

Code

    def intervalIntersection(firstList, secondList):
    """
    Finds the intersection of two lists of closed intervals.

    Args:
        firstList: A list of closed intervals.
        secondList: A list of closed intervals.

    Returns:
        A list of closed intervals representing the intersection.
    """

    result = []
    i, j = 0, 0

    while i < len(firstList) and j < len(secondList):
        start_i, end_i = firstList[i]
        start_j, end_j = secondList[j]

        # Calculate intersection
        start_intersect = max(start_i, start_j)
        end_intersect = min(end_i, end_j)

        if start_intersect <= end_intersect:
            result.append([start_intersect, end_intersect])

        # Advance pointer
        if end_i < end_j:
            i += 1
        else:
            j += 1

    return result