leetcode 773. Sliding Puzzle
On a 2x3 board, there are 5 tiles represented by the integers 1 through 5, and an empty square represented by 0.A move consists of choosing 0 and a 4-directionally adjacent number and swapping it.
The state of the board is solved if and only if the board is [,].
Given a puzzle board, return the least number of moves required so that the state of the board is solved. If it is impossible for the state of the board to be solved, return -1.
Examples:
Input: board = [,]
Output: 1
Explanation: Swap the 0 and the 5 in one move.
Input: board = [,]
Output: -1
Explanation: No number of moves will make the board solved.
Input: board = [,]
Output: 5
Explanation: 5 is the smallest number of moves that solves the board.
An example path:
After move 0: [,]
After move 1: [,]
After move 2: [,]
After move 3: [,]
After move 4: [,]
After move 5: [,]
Input: board = [,]
Output: 14
Note:
board will be a 2 x 3 array as described above.
board will be a permutation of .
class Solution:
def slidingPuzzle(self, board: List]) -> int:
start, goal = "", ""
row_len, col_len = 2, 3
for i in range(len(board)):
for j in range(len(board)):
goal += str((i * col_len + j + 1) % (row_len * col_len))
start += str(board)
if start == goal:
return 0
directions = [, , , [-1, 0]]
queue = []
visited = set()
queue.append(start)
visited.add(start)
steps = 0
while queue:
steps += 1
size = len(queue)
for _ in range(size):
cur = queue.pop(0)
p = cur.find('0')
x = p % col_len
y = p // col_len
for direction in directions:
new_x = x + direction
new_y = y + direction
if new_x < 0 or new_x >= col_len or new_y < 0 or new_y >= row_len:
continue
pp = new_y * col_len + new_x
if pp < 0 or pp >= 6:
continue
new_cur = cur[:]
new_str = list(new_cur)
new_str, new_str = new_str, new_str
new_cur = "".join(new_str)
if new_cur in visited:
continue
if new_cur == goal:
return steps
visited.add(new_cur)
queue.append(new_cur)
return -1
页:
[1]