Sort the Matrix Diagonally

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.

Example 1:

Input: mat = [[3,3,1,1],[2,2,1,2],[1,1,1,2]]
Output: [[1,1,1,1],[1,2,2,2],[1,2,3,3]]

Example 2:

Input: mat = [[11,25,66,1,69,7],[23,55,17,45,15,52],[75,31,36,44,58,8],[22,27,33,25,68,4],[84,28,14,11,5,50]]
Output: [[5,17,4,1,52,7],[11,11,25,45,8,69],[14,23,25,44,58,15],[22,27,31,36,50,66],[84,28,75,33,55,68]]

Constraints:

• m == mat.length
• n == mat[i].length
• 1 <= m, n <= 100
• 1 <= mat[i][j] <= 100

SOLUTION:

import bisect

class Solution:
    def diagonalSort(self, mat: List[List[int]]) -> List[List[int]]:
        m = len(mat)
        n = len(mat[0])
        diags = {}
        for i in range(m):
            for j in range(n):
                if i - j in diags:
                    bisect.insort(diags[i - j], mat[i][j])
                else:
                    diags[i - j] = [mat[i][j]]
        for i in range(m):
            for j in range(n):
                mat[i][j] = diags[i - j][min(i, j)]
        return mat

# import bisect

# class Solution:
#     def diagonalSort(self, mat: List[List[int]]) -> List[List[int]]:
#         m = len(mat)
#         n = len(mat[0])
#         vals = [[] for i in range(m + n - 1)]
#         curr = 0
#         for i in range(m):
#             x, y = i, 0
#             while x < m and y < n:
#                 bisect.insort(vals[curr], mat[x][y])
#                 x += 1
#                 y += 1
#             curr += 1
#         for i in range(1, n):
#             x, y = 0, i
#             while x < m and y < n:
#                 bisect.insort(vals[curr], mat[x][y])
#                 x += 1
#                 y += 1
#             curr += 1
#         curr = 0
#         for i in range(m):
#             x, y = i, 0
#             while x < m and y < n:
#                 mat[x][y] = vals[curr][y]
#                 x += 1
#                 y += 1
#             curr += 1
#         for i in range(1, n):
#             x, y = 0, i
#             while x < m and y < n:
#                 mat[x][y] = vals[curr][x]
#                 x += 1
#                 y += 1
#             curr += 1
#         return mat