Data commit

Task/15-puzzle-game/Go/15-puzzle-game.go

@@ -0,0 +1,154 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"strings"
+	"time"
+)
+
+func main() {
+	rand.Seed(time.Now().UnixNano())
+	p := newPuzzle()
+	p.play()
+}
+
+type board [16]cell
+type cell uint8
+type move uint8
+
+const (
+	up move = iota
+	down
+	right
+	left
+)
+
+func randMove() move { return move(rand.Intn(4)) }
+
+var solvedBoard = board{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0}
+
+func (b *board) String() string {
+	var buf strings.Builder
+	for i, c := range b {
+		if c == 0 {
+			buf.WriteString("  .")
+		} else {
+			_, _ = fmt.Fprintf(&buf, "%3d", c)
+		}
+		if i%4 == 3 {
+			buf.WriteString("\n")
+		}
+	}
+	return buf.String()
+}
+
+type puzzle struct {
+	board board
+	empty int // board[empty] == 0
+	moves int
+	quit  bool
+}
+
+func newPuzzle() *puzzle {
+	p := &puzzle{
+		board: solvedBoard,
+		empty: 15,
+	}
+	// Could make this configurable, 10==easy, 50==normal, 100==hard
+	p.shuffle(50)
+	return p
+}
+
+func (p *puzzle) shuffle(moves int) {
+	// As with other Rosetta solutions, we use some number
+	// of random moves to "shuffle" the board.
+	for i := 0; i < moves || p.board == solvedBoard; {
+		if p.doMove(randMove()) {
+			i++
+		}
+	}
+}
+
+func (p *puzzle) isValidMove(m move) (newIndex int, ok bool) {
+	switch m {
+	case up:
+		return p.empty - 4, p.empty/4 > 0
+	case down:
+		return p.empty + 4, p.empty/4 < 3
+	case right:
+		return p.empty + 1, p.empty%4 < 3
+	case left:
+		return p.empty - 1, p.empty%4 > 0
+	default:
+		panic("not reached")
+	}
+}
+
+func (p *puzzle) doMove(m move) bool {
+	i := p.empty
+	j, ok := p.isValidMove(m)
+	if ok {
+		p.board[i], p.board[j] = p.board[j], p.board[i]
+		p.empty = j
+		p.moves++
+	}
+	return ok
+}
+
+func (p *puzzle) play() {
+	fmt.Printf("Starting board:")
+	for p.board != solvedBoard && !p.quit {
+		fmt.Printf("\n%v\n", &p.board)
+		p.playOneMove()
+	}
+	if p.board == solvedBoard {
+		fmt.Printf("You solved the puzzle in %d moves.\n", p.moves)
+	}
+}
+
+func (p *puzzle) playOneMove() {
+	for {
+		fmt.Printf("Enter move #%d (U, D, L, R, or Q): ", p.moves+1)
+		var s string
+		if n, err := fmt.Scanln(&s); err != nil || n != 1 {
+			continue
+		}
+
+		s = strings.TrimSpace(s)
+		if s == "" {
+			continue
+		}
+
+		var m move
+		switch s[0] {
+		case 'U', 'u':
+			m = up
+		case 'D', 'd':
+			m = down
+		case 'L', 'l':
+			m = left
+		case 'R', 'r':
+			m = right
+		case 'Q', 'q':
+			fmt.Printf("Quiting after %d moves.\n", p.moves)
+			p.quit = true
+			return
+		default:
+			fmt.Println(`
+Please enter "U", "D", "L", or "R" to move the empty cell
+up, down, left, or right. You can also enter "Q" to quit.
+Upper or lowercase is accepted and only the first non-blank
+character is important (i.e. you may enter "up" if you like).
+`)
+			continue
+		}
+
+		if !p.doMove(m) {
+			fmt.Println("That is not a valid move at the moment.")
+			continue
+		}
+
+		return
+	}
+}