Skip to content

1424. Diagonal Traverse II

Difficulty Topics

Description

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

Solution

diagonal-traverse-ii.py
class Solution:
    def findDiagonalOrder(self, nums: List[List[int]]) -> List[int]:

        mp = collections.defaultdict(list)

        for i, r in enumerate(nums):
            for j,v in enumerate(r):
                mp[i+j].append(v)

        return [v for key in mp for v in mp[key][::-1] ]