Leetcode 1424. Diagonal Traverse II

Seawolf

1. Given a list of lists of integers, nums, return all elements of nums in diagonal order as shown in the below images.
   
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4. Example 1:
   
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8. Input: nums = [[1,2,3],[4,5,6],[7,8,9]]
   
9. Output: [1,4,2,7,5,3,8,6,9]
   
10. Example 2:
    
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14. Input: nums = [[1,2,3,4,5],[6,7],[8],[9,10,11],[12,13,14,15,16]]
    
15. Output: [1,6,2,8,7,3,9,4,12,10,5,13,11,14,15,16]
    
16. Example 3:
    
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18. Input: nums = [[1,2,3],[4],[5,6,7],[8],[9,10,11]]
    
19. Output: [1,4,2,5,3,8,6,9,7,10,11]
    
20. Example 4:
    
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22. Input: nums = [[1,2,3,4,5,6]]
    
23. Output: [1,2,3,4,5,6]
    
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26. Constraints:
    
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28. 1 <= nums.length <= 10^5
    
29. 1 <= nums[i].length <= 10^5
    
30. 1 <= nums[i][j] <= 10^9
    
31. There at most 10^5 elements in nums.

复制代码

1. class Solution:
   
2.     def findDiagonalOrder(self, nums: List[List[int]]) -> List[int]:
   
3.         result = []
   
4.         if nums == None or len(nums) == 0:
   
5.             return result
   
6.         hashmap = collections.defaultdict(list)
   
7.         m = len(nums)
   
8.         for i in range(m):
   
9.             for j in range(len(nums[i])):
   
10.                 hashmap[i + j].append(nums[i][j])
    
11.         for k in sorted(hashmap.keys()):
    
12.             temp = hashmap[k]
    
13.             temp = temp[::-1]
    
14.             result += temp
    
15.         return result
    
16.         

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