September 2017 Update

Task/Sudoku/Swift/sudoku-1.swift

@@ -111,7 +111,6 @@ let board = [
     [4, 0, 0, 0, 0, 0, 0, 6, 0],
     [5, 0, 0, 0, 8, 0, 9, 0, 0],
     [3, 0, 0, 0, 0, 1, 0, 0, 0],
-
     [0, 2, 0, 7, 0, 0, 0, 0, 1],
     [0, 9, 0, 0, 0, 0, 0, 4, 0],
     [8, 0, 0, 0, 0, 3, 0, 5, 0],

Task/Sudoku/Swift/sudoku-2.swift

@@ -0,0 +1,64 @@
+func solving(board: [[Int]]) -> [[Int]] {
+	var board = board
+	var isSolved = false
+	while !isSolved {
+		for x in 0 ..< 9  {
+			for y in 0 ..< 9 {
+				if board[x][y] == 0 {
+					let known = Set(board.map { $0[y] } + board[x] + subgrid(board, pos: (x, y)))
+					let possible = Set(Array(1...9)).subtracting(known)
+					if possible.count == 1  {
+						board[x][y] = possible.first!
+					}
+				}
+			}
+			isSolved = 45 == board[x].reduce(0, +)
+		}
+	}
+	return board
+}
+
+func subgrid(_ board: [[Int]], pos: (Int, Int)) -> [Int] {
+	var r = [Int]()
+	var (x, y) = pos
+	x = x / 3 * 3
+	y = y / 3 * 3
+	for i in x ..< x + 3 {
+		for j in y ..< y + 3 {
+			r.append(board[i][j])
+		}
+	}
+	return r
+}
+
+func print(_ board: [[Int]]) {
+	for i in board.indices {
+		if i % 9 == 0 {
+			print(" -------------------")
+		}
+		for j in board.indices {
+			if j % board.count == 0 {
+				print("| ", terminator: "")
+			}
+			let digit = board[i][j]
+			print(digit != 0 ? digit : " ", terminator: "")
+			print(" ", terminator: "")
+		}
+		print("|")
+	}
+	print(" -------------------")
+}
+
+let puzzle = [
+	[0,2,0,4,5,0,7,0,9],
+	[0,0,0,1,0,9,0,3,0],
+	[0,0,8,0,0,0,1,0,4],
+	[0,4,0,0,6,1,0,7,0],
+	[5,0,6,0,3,0,0,1,0],
+	[0,3,0,0,0,2,0,9,0],
+	[3,0,4,0,7,5,0,6,8],
+	[0,9,0,0,1,0,3,0,7],
+	[0,0,2,0,0,3,0,0,1]
+]
+
+print(solving(board: puzzle))