Medium

Quiz

#1424 Diagonal Traverse II

APPROACH

Given a 2D integer array nums (rows may have different lengths), return all elements traversed in diagonal order: group elements by their i + j sum (same diagonal), and within each diagonal collect elements in order of increasing column index j.

Example 1:

Input: nums = [[1,2,3],[4,5,6],[7,8,9]]

Output: [1,4,2,7,5,3,8,6,9]

Example 2:

Input: nums = [[1,2,3,4,5],[6,7],[8],[9,10,11],[12,13,14,15,16]]

Output: [1,6,2,8,7,3,9,4,12,10,5,13,11,14,15,16]

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What is the optimal approach for this problem?