feat(day 160): calculate valid knight moves on a chessboard from a given position

Author: JohnSunny21

FreeCodeCamp/CodingQ/KnightMoves.py

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+"""  
+
+Knight Moves
+Given the position of a knight on a chessboard, return the number of valid squares the knight can move to.
+
+A standard chessboard is 8x8, with columns labeled A through H (left to right) and rows labeled 1 through 8 (bottom to top). It looks like this:
+
+A8	B8	C8	D8	E8	F8	G8	H8
+A7	B7	C7	D7	E7	F7	G7	H7
+A6	B6	C6	D6	E6	F6	G6	H6
+A5	B5	C5	D5	E5	F5	G5	H5
+A4	B4	C4	D4	E4	F4	G4	H4
+A3	B3	C3	D3	E3	F3	G3	H3
+A2	B2	C2	D2	E2	F2	G2	H2
+A1	B1	C1	D1	E1	F1	G1	H1
+A knight moves in an "L" shape: two squares in one direction (horizontal or vertical), and one square in the perpendicular direction.
+
+This means a knight can move to up to eight possible positions, but fewer when near the edges of the board. For example, if a knight was at A1, it could only move to B3 or C2.
+"""
+
+import unittest
+
+class KnightMovesTest(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(knight_moves("A1"), 2)
+
+    def test2(self):
+        self.assertEqual(knight_moves("D4"), 8)
+
+    def test3(self):
+        self.assertEqual(knight_moves("G6"), 6)
+
+    def test4(self):
+        self.assertEqual(knight_moves("B8"), 3)
+
+    def test5(self):
+        self.assertEqual(knight_moves("H3"), 4)
+
+
+def knight_moves(position):
+
+    col = ord(position[0].upper()) - ord('A') + 1
+    row = int(position[1])
+
+
+    moves = [
+        (2, 1) ,(2, -1), (-2, 1), (-2, -1),
+        (1, -2), (1, 2), (-1, 2), (-1, -2)
+    ]
+    valid_moves = 0
+
+    for dx, dy in moves:
+        new_col = col + dx
+        new_row = row + dy
+        if 1 <= new_col <= 8 and 1 <= new_row <= 8:
+            valid_moves += 1
+
+    return valid_moves
+
+
+""" 
+
+=> Convert chess notation -> numeric coordinates.
+=> apply knight's 8 possible moves.
+=> count only those withn the 8x8 board. 
+
+
+we can also extend it for show the valid squares rather than just showing only the count
+
+
+"""
+
+
+def knight_moves_positions(position):
+
+    col = ord(position[0].upper()) - ord('A') + 1
+    row = int(position[1])
+
+    moves = [
+        (2, 1), (2, -1), (-2, 1), (-2, -1),
+        (1, -2), (1, 2), (-1, 2), (-1, -2)
+    ]
+
+    valid_positions = []
+    for dx, dy in moves:
+        new_col = col + dx
+        new_row = row + dy
+
+        if 1 <= new_col <= 8 and 1 <= new_row <= 8:
+            square = chr(ord('A') + new_col - 1) + str(new_row)
+            valid_positions.append(square)
+
+
+    return valid_positions
+
+if __name__ == "__main__":
+    print(knight_moves("D6"))
+
+    print(knight_moves_positions("D6"))
+    unittest.main()