diagonal-traverse-ii

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1424. Diagonal Traverse II (Medium)

Given a 2D integer array nums, return all elements of nums in diagonal order as shown in the below images.

 

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]

 

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i].length <= 105
• 1 <= sum(nums[i].length) <= 105
• 1 <= nums[i][j] <= 105

Related Topics

[Array] [Sorting] [Heap (Priority Queue)]

Hints

Hint 1

Notice that numbers with equal sums of row and column indexes belong to the same diagonal.

Hint 2

Store them in tuples (sum, row, val), sort them, and then regroup the answer.