Merge pull request #11 from andrerademacher/10-shortest-knight-path

done!

kata/ShortestKnightPath/Knight.py

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+SIZE = 8
+EMPTY = -1
+POSSIBLE_MOVES = [(1, 2), (2, 1), (-1, 2), (-2, 1), (1, -2), (2, -1), (-1, -2), (-2, -1)]
+
+def knight(p1, p2) -> int:
+
+    start = toCoordinates(p1)
+    end = toCoordinates(p2)
+    board = [ [EMPTY]*SIZE for line in range(SIZE)]
+    board[start[0]][start[1]] = 0
+
+    moves = 0
+    while board[end[0]][end[1]] == EMPTY:
+        for x in range(SIZE):
+            for y in range(SIZE):
+                if board[x][y] == moves:
+                    for delta in POSSIBLE_MOVES:
+                        newX = x + delta[0]
+                        newY = y + delta[1]
+                        if 0 <= newX and newX < SIZE and 0 <= newY and newY < SIZE:
+                            board[newX][newY] = moves + 1 
+
+        moves+=1
+    return moves
+
+# transforms the algebraic string notation (e.g. 'e4') into numeric, zero based coordinates [4, 3]
+def toCoordinates(algebraicNotation: str) -> list:
+    return [ord(algebraicNotation[0:1]) - ord('a'), int(algebraicNotation[1:2]) - 1]

kata/ShortestKnightPath/README.md

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+# Shortest Knight Path
+
+Given two different positions on a chess board, find the least number of moves it would take a knight to get from one to the other. The positions will be passed as two arguments in algebraic notation. For example, `knight("a3", "b5")` should return 1.
+
+The knight is not allowed to move off the board. The board is 8x8.
+
+For information on knight moves, see https://en.wikipedia.org/wiki/Knight_%28chess%29
+
+For information on algebraic notation, see https://en.wikipedia.org/wiki/Algebraic_notation_%28chess%29
+
+(Warning: many of the tests were generated randomly. If any do not work, the test cases will return the input, output, and expected output; please post them.)
+
+[See this kata in Codewars](https://www.codewars.com/kata/549ee8b47111a81214000941)

kata/ShortestKnightPath/test_Knight.py

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+import codewars_test as test
+from Knight import knight
+
+
+@test.describe("Shortest knight path")
+def shortest_night_path_test():
+    @test.it("starting at a1")
+    def a1_tests():
+#        test.assert_equals(knight('a1', 'c1'), 2)
+#        test.assert_equals(knight('a1', 'f1'), 3)
+#        test.assert_equals(knight('a1', 'f3'), 3)
+#        test.assert_equals(knight('a1', 'f4'), 4)
+#        test.assert_equals(knight('a1', 'f7'), 5)
+        test.assert_equals(knight('d1', 'a2'), 2)