LeetCode 986. Interval List Intersections

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题目

Given two lists of closed intervals, each list of intervals is pairwise disjoint and in sorted order.

Return the intersection of these two interval lists.

(Formally, 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 is either empty, or can be represented as a closed interval. For example, the intersection of [1, 3] and [2, 4] is [2, 3].)

Example 1:

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Input: A = [[0,2],[5,10],[13,23],[24,25]], B = [[1,5],[8,12],[15,24],[25,26]]
Output: [[1,2],[5,5],[8,10],[15,23],[24,24],[25,25]]
Reminder: The inputs and the desired output are lists of Interval objects, and not arrays or lists.

Note:

  • 0 <= A.length < 1000
  • 0 <= B.length < 1000
  • 0 <= A[i].start, A[i].end, B[i].start, B[i].end < 10^9

NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

思路

双指针。

代码

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class Solution(object):
    def intervalIntersection(self, A, B):
        """
        :type A: List[List[int]]
        :type B: List[List[int]]
        :rtype: List[List[int]]
        """
        res = []
        i, j = 0, 0
        if not A or not B:
            return res
        while i < len(A) and j < len(B):
            l = max(A[i][0], B[j][0])
            r = min(A[i][1], B[j][1])
            if l <= r:
                interval = [l, r]
                res.append(interval)
            if A[i][1] < B[j][1]:
                i += 1
            else:
                j += 1
        return res