From 0989a2c86ecb9e4cedc5d4ce7d5c5dcba9448f5a Mon Sep 17 00:00:00 2001
From: anubhav-qt <magicalfizz@gmail.com>
Date: Thu, 3 Oct 2024 20:57:50 +0530
Subject: [PATCH 1/5] Add diagonal matrix traversal algorithm

---
 matrix/diagonal_traversal.py | 67 ++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 matrix/diagonal_traversal.py

diff --git a/matrix/diagonal_traversal.py b/matrix/diagonal_traversal.py
new file mode 100644
index 000000000000..bc8702b7535e
--- /dev/null
+++ b/matrix/diagonal_traversal.py
@@ -0,0 +1,67 @@
+from typing import List
+
+def find_diagonal_order(mat: List[List[int]]) -> List[int]:
+    """
+    Returns the elements of the matrix in diagonal order.
+
+    :param mat: A 2D list representing the matrix.
+    :return: A list of elements in diagonal order.
+    :raises ValueError: If the matrix is empty or rows have different lengths.
+
+    >>> find_diagonal_order([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
+    [1, 2, 4, 7, 5, 3, 6, 8, 9]
+
+    Example:
+    matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
+    Algorithm:
+        Step 1. Initialize variables to track the current row and column.
+        Step 2. Iterate through the elements of the matrix in a
+                manner that alternates between moving diagonally up
+                and down.
+    """
+    if not mat or not mat[0]:
+        return []
+
+    m, n = len(mat), len(mat[0])
+
+    # Check for uniformity of row lengths
+    for row in mat:
+        if len(row) != n:
+            raise ValueError("All rows must have the same number of columns.")
+
+    result = []
+    row, col = 0, 0
+
+    for _ in range(m * n):
+        result.append(mat[row][col])
+
+        # Determine the direction of traversal
+        if (row + col) % 2 == 0:  # moving up
+            if col == n - 1:  # hit the right boundary
+                row += 1
+            elif row == 0:  # hit the top boundary
+                col += 1
+            else:  # move up diagonally
+                row -= 1
+                col += 1
+        else:  # moving down
+            if row == m - 1:  # hit the bottom boundary
+                col += 1
+            elif col == 0:  # hit the left boundary
+                row += 1
+            else:  # move down diagonally
+                row += 1
+                col -= 1
+
+    return result
+
+
+# Driver code
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+
+    # Example usage
+    matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
+    print(find_diagonal_order(matrix))

From 9898007442525c4307a89041af52cccca1d670c5 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 3 Oct 2024 15:35:30 +0000
Subject: [PATCH 2/5] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 matrix/diagonal_traversal.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/matrix/diagonal_traversal.py b/matrix/diagonal_traversal.py
index bc8702b7535e..418505689b9a 100644
--- a/matrix/diagonal_traversal.py
+++ b/matrix/diagonal_traversal.py
@@ -1,5 +1,6 @@
 from typing import List
 
+
 def find_diagonal_order(mat: List[List[int]]) -> List[int]:
     """
     Returns the elements of the matrix in diagonal order.

From ba3cf0aa0065f60e86035d9fdb52c3f218de2008 Mon Sep 17 00:00:00 2001
From: Anubhav Joshi <48016317+anubhav-qt@users.noreply.github.com>
Date: Thu, 3 Oct 2024 21:14:11 +0530
Subject: [PATCH 3/5] Update diagonal_traversal.py to pass ruff test

---
 matrix/diagonal_traversal.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/matrix/diagonal_traversal.py b/matrix/diagonal_traversal.py
index 418505689b9a..b44447e12c13 100644
--- a/matrix/diagonal_traversal.py
+++ b/matrix/diagonal_traversal.py
@@ -1,7 +1,7 @@
-from typing import List
+from typing import list
 
 
-def find_diagonal_order(mat: List[List[int]]) -> List[int]:
+def find_diagonal_order(mat: list[list[int]]) -> list[int]:
     """
     Returns the elements of the matrix in diagonal order.
 

From 204c38836bcb538f40d78fdb8ba0dc61e2c62100 Mon Sep 17 00:00:00 2001
From: Anubhav Joshi <48016317+anubhav-qt@users.noreply.github.com>
Date: Sat, 5 Oct 2024 19:12:43 +0530
Subject: [PATCH 4/5] Update diagonal_traversal.py to adhere ruff suggestions

---
 matrix/diagonal_traversal.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/matrix/diagonal_traversal.py b/matrix/diagonal_traversal.py
index b44447e12c13..88bd28d39333 100644
--- a/matrix/diagonal_traversal.py
+++ b/matrix/diagonal_traversal.py
@@ -45,14 +45,14 @@ def find_diagonal_order(mat: list[list[int]]) -> list[int]:
             else:  # move up diagonally
                 row -= 1
                 col += 1
-        else:  # moving down
-            if row == m - 1:  # hit the bottom boundary
-                col += 1
-            elif col == 0:  # hit the left boundary
-                row += 1
-            else:  # move down diagonally
-                row += 1
-                col -= 1
+        elif row == m - 1:  # hit the bottom boundary
+            col += 1
+        elif col == 0:  # hit the left boundary
+            row += 1
+        elif col > 0 and row < m - 1:  # move down diagonally
+            row += 1
+            col -= 1
+
 
     return result
 

From 621a09f07446bbc7bd54d682dce1be512080ba3d Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 5 Oct 2024 13:45:05 +0000
Subject: [PATCH 5/5] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 matrix/diagonal_traversal.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/matrix/diagonal_traversal.py b/matrix/diagonal_traversal.py
index 88bd28d39333..2ed9f3d7c712 100644
--- a/matrix/diagonal_traversal.py
+++ b/matrix/diagonal_traversal.py
@@ -53,7 +53,6 @@ def find_diagonal_order(mat: list[list[int]]) -> list[int]:
             row += 1
             col -= 1
 
-
     return result