题目
A matrix diagonal is a diagonal line of cells starting from some cell in either the topmost row or leftmost column and going in the bottom-right direction until reaching the matrix’s end. For example, the matrix diagonal starting from mat[2][0], where mat is a 6 x 3 matrix, includes cells mat[2][0], mat[3][1], and mat[4][2].
Given an m x n matrix mat of integers, sort each matrix diagonal in ascending order and return the resulting matrix.
解题思路
同一对角线的坐标差相同，使用字典加优先队列把相同对角线的数排序，依次pop重建
代码
class Solution:
def diagonalSort(self, mat: List[List[int]]) -> List[List[int]]:
dic = defaultdict(list)
m, n = len(mat), len(mat[0])
for i in range(m):
for j in range(n):
heappush(dic[i - j], mat[i][j])
for i in range(m):
for j in range(n):
mat[i][j] = heappop(dic[i - j])
return mat
