题目：原题链接（中等）
标签：广度优先搜索
解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
Ans 1 (Python) | O ( N ) | O ( N ) | 108ms (100.00%) |
Ans 2 (Python) | |||
Ans 3 (Python) |
解法一：
class Solution:
def snakesAndLadders(self, board: List[List[int]]) -> int:
m, n = len(board), len(board[0])
# 将蛇形棋转换为列表
lst = [0]
reverse = False
for i in range(m - 1, -1, -1):
if not reverse:
lst.extend(board[i])
else:
lst.extend(reversed(board[i]))
reverse = not reverse
# 广度优先搜索
step = 0
visited = {1: 0}
queue = collections.deque([1])
while queue:
step += 1
for _ in range(len(queue)):
n1 = queue.popleft()
for n2 in range(n1 + 1, n1 + 7):
if n2 == m * n:
return step
if lst[n2] != -1:
n2 = lst[n2]
if n2 == m * n:
return step
if n2 not in visited or visited[n2] > step:
visited[n2] = step
queue.append(n2)
return -1
