README.md

1424. Diagonal Traverse II

Given a list of lists of integers, 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]

Example 3:

Input: nums = [[1,2,3],[4],[5,6,7],[8],[9,10,11]]
Output: [1,4,2,5,3,8,6,9,7,10,11]

Example 4:

Input: nums = [[1,2,3,4,5,6]]
Output: [1,2,3,4,5,6]

Constraints:

• 1 <= nums.length <= 10^5
• 1 <= nums[i].length <= 10^5
• 1 <= nums[i][j] <= 10^9
• There at most 10^5 elements in nums.

Solutions (Ruby)

1. Sort

# @param {Integer[][]} nums
# @return {Integer[]}
def find_diagonal_order(nums)
    num_row_col = []

    for row in 0...nums.length
        for col in 0...nums[row].length
            num_row_col.push([nums[row][col], row, col])
        end
    end

    num_row_col.sort_by! {|nrc| nrc[2]}
    num_row_col.sort_by! {|nrc| nrc[1] + nrc[2]}

    return num_row_col.map {|nrc| nrc[0]}
end