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package main | |
// run this: https://play.golang.org/p/lGEbAcNeVJr | |
import ( | |
"fmt" | |
"log" | |
) | |
const ( | |
Left = iota | |
Right | |
) | |
type direction int | |
type move struct { | |
Direction direction | |
Letter *string | |
} | |
func rotateLeft(letters []string, pos int) ([]move, []string) { | |
letter := letters[pos] | |
moves := make([]move, pos+1) | |
for i := 0; i < pos; i++ { | |
first := letters[0] | |
for j := 1; j < len(letters); j++ { | |
letters[j-1] = letters[j] | |
} | |
letters[len(letters)-1] = first | |
moves[i] = move{Direction: Left} | |
} | |
moves[pos] = move{Direction: Left, Letter: &letter} | |
return moves, letters[1:] | |
} | |
func rotateRight(letters []string, pos int) ([]move, []string) { | |
letter := letters[pos] | |
moves := make([]move, len(letters)-pos) | |
k := 0 | |
for i := len(letters) - 1; i > pos; i-- { | |
last := letters[len(letters)-1] | |
for j := len(letters) - 2; j >= 0; j-- { | |
letters[j+1] = letters[j] | |
} | |
letters[0] = last | |
moves[k] = move{Direction: Right} | |
k++ | |
} | |
moves[k] = move{Direction: Right, Letter: &letter} | |
return moves, letters[:len(letters)-1] | |
} | |
func findPos(letters []string, pat string) (direction, int, error) { | |
left := 0 | |
right := len(letters) - 1 | |
for left <= right { | |
if letters[left] == pat { | |
return Left, left, nil | |
} | |
if letters[right] == pat { | |
return Right, right, nil | |
} | |
left++ | |
right-- | |
} | |
return -1, -1, fmt.Errorf("%s not found", pat) | |
} | |
func printMoves(moves []move) { | |
for _, move := range moves { | |
if move.Direction == Left { | |
fmt.Printf("LEFT: ") | |
} else { | |
fmt.Printf("RIGHT: ") | |
} | |
if move.Letter != nil { | |
fmt.Printf(" %s\n", *move.Letter) | |
} else { | |
fmt.Printf(" nil\n") | |
} | |
} | |
} | |
func playGame(in []string, pat []string) ([]move, []string, error) { | |
board := make([]string, len(in)) | |
copy(board, in) | |
moves := make([]move, 0) | |
for _, p := range pat { | |
//fmt.Printf("current board: %v\n", board) | |
dir, pos, err := findPos(board, p) | |
if err != nil { | |
return nil, nil, err | |
} | |
var turnMoves []move | |
if dir == Left { | |
turnMoves, board = rotateLeft(board, pos) | |
moves = append(moves, turnMoves...) | |
} else { | |
turnMoves, board = rotateRight(board, pos) | |
moves = append(moves, turnMoves...) | |
} | |
} | |
return moves, board, nil | |
} | |
func main() { | |
in := []string{"a", "z", "c", "t", "v", "b"} | |
pat := []string{"z", "b"} | |
fmt.Printf("input board: %v, pat: %v\n", in, pat) | |
moves, board, err := playGame(in, pat) | |
if err != nil { | |
log.Fatal(err) | |
} | |
printMoves(moves) | |
fmt.Printf("post-play working board %v\n", board) | |
in = []string{"a", "z", "c", "t", "v", "b"} | |
pat = []string{"c", "t"} | |
fmt.Printf("\ninput board: %v, pat: %v\n", in, pat) | |
moves, board, err = playGame(in, pat) | |
if err != nil { | |
log.Fatal(err) | |
} | |
printMoves(moves) | |
fmt.Printf("post-play working board %v\n", board) | |
in = []string{"a", "z", "c", "t", "v", "a"} | |
pat = []string{"c", "a", "t"} | |
fmt.Printf("\ninput board: %v, pat: %v\n", in, pat) | |
moves, board, err = playGame(in, pat) | |
if err != nil { | |
log.Fatal(err) | |
} | |
printMoves(moves) | |
fmt.Printf("post-play working board %v\n", board) | |
in = []string{"a", "z", "c", "t", "v", "a"} | |
pat = []string{"t", "v"} | |
fmt.Printf("\ninput board: %v, pat: %v\n", in, pat) | |
moves, board, err = playGame(in, pat) | |
if err != nil { | |
log.Fatal(err) | |
} | |
printMoves(moves) | |
fmt.Printf("post-play working board %v\n", board) | |
in = []string{"a"} | |
pat = []string{"a"} | |
fmt.Printf("\ninput board: %v, pat: %v\n", in, pat) | |
moves, board, err = playGame(in, pat) | |
if err != nil { | |
log.Fatal(err) | |
} | |
printMoves(moves) | |
fmt.Printf("post-play working board %v\n", board) | |
in = []string{"a"} | |
pat = []string{"b"} | |
fmt.Printf("\ninput board: %v, pat: %v\n", in, pat) | |
moves, board, err = playGame(in, pat) | |
if err == nil { | |
log.Fatal("should not be found") | |
} | |
} |
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