Hard

Quiz

#632 Smallest Range Covering Elements from K Lists

APPROACH

Given k sorted lists of integers, find the smallest interval [a, b] that contains at least one element from every list. An interval [a, b] is considered smaller than [c, d] if its length is shorter, or if lengths are equal, if a < c.

Example 1:

Input: nums = [[4,10,15,24,26],[0,9,12,20],[5,18,22,30]]

Output: [20,24]

Explanation:

List 1: [4, 10, 15, 24,26], 24 is in range [20,24].

List 2: [0, 9, 12, 20], 20 is in range [20,24].

List 3: [5, 18, 22, 30], 22 is in range [20,24].

Example 2:

Input: nums = [[1,2,3],[1,2,3],[1,2,3]]

Output: [1,1]

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What is the optimal approach for this problem?