D. J.:

- Added the leetcode problem and solution for 3346

Author: nobodyPerfecZ

README.md

@@ -297,6 +297,7 @@
 - [3136 Valid Word](https://leetcode.com/problems/valid-word/description/)
 - [3202 Find the Maximum Length of Valid Subsequence II](https://leetcode.com/problems/find-the-maximum-length-of-valid-subsequence-ii/description/)
 - [3392 Count Subarrays of Length Three With a Condition](https://leetcode.com/problems/count-subarrays-of-length-three-with-a-condition/description/)
+- [3446 Sort Matrix by Diagonals](https://leetcode.com/problems/sort-matrix-by-diagonals/description/)
 
 ## Development 🔧
 

awesome_python_leetcode/_3446_sort_matrix_by_diagonals.py

@@ -0,0 +1,40 @@
+from typing import List
+
+
+class Solution:
+    """Base class for all LeetCode Problems."""
+
+    def sortMatrix(self, grid: List[List[int]]) -> List[List[int]]:
+        """
+        You are given an n x n square matrix of integers grid. Return the matrix such
+        that:
+        - The diagonals in the bottom-left triangle (including the middle diagonal) are
+        sorted in non-increasing order.
+        - The diagonals in the top-right triangle are sorted in non-decreasing order.
+        """
+        # Collect diagonals
+        diag = {}
+        for i in range(len(grid)):
+            for j in range(len(grid[0])):
+                key = i - j
+                if key not in diag:
+                    diag[key] = []
+                diag[key].append(grid[i][j])
+
+        # Sort in decreasing / increasing order for each diagonal
+        diag = dict(
+            zip(
+                diag.keys(),
+                map(lambda key: sorted(diag[key], reverse=(key >= 0)), diag.keys()),
+                strict=False,
+            )
+        )
+
+        # Apply the sorted diagonals to the result matrix
+        result = [[0 for _ in range(len(grid[0]))] for _ in range(len(grid))]
+        for i in range(len(grid)):
+            for j in range(len(grid[0])):
+                key = i - j
+                result[i][j] = diag[key].pop(0)
+
+        return result

tests/test_3446_sort_matrix_by_diagonals.py

@@ -0,0 +1,19 @@
+from typing import List
+
+import pytest
+
+from awesome_python_leetcode._3446_sort_matrix_by_diagonals import Solution
+
+
+@pytest.mark.parametrize(
+    argnames=["grid", "expected"],
+    argvalues=[
+        ([[1, 7, 3], [9, 8, 2], [4, 5, 6]], [[8, 2, 3], [9, 6, 7], [4, 5, 1]]),
+        ([[0, 1], [1, 2]], [[2, 1], [1, 0]]),
+        ([[1]], [[1]]),
+    ],
+)
+def test_func(grid: List[List[int]], expected: List[List[int]]):
+    """Tests the solution of a LeetCode problem."""
+    sorted_grid = Solution().sortMatrix(grid)
+    assert sorted_grid == expected