题目
Given an m x n matrix mat, return an array of all the elements of the array in a diagonal order.
解题思路
i+j相同的数在一组，偶数翻转
代码
class Solution:
def findDiagonalOrder(self, matrix: List[List[int]]) -> List[int]:
m = len(matrix)
n = len(matrix[0])
dic = defaultdict(list)
for i in range(m):
for j in range(n):
dic[(i + j)].append(matrix[i][j])
res = []
for i in range(m + n - 1):
if i % 2:
res.extend(dic[i])
else:
res.extend(dic[i][::-1])
return res
