47 lines
1.6 KiB
Python
47 lines
1.6 KiB
Python
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class Solution:
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def snakesAndLadders(self, board: List[List[int]]) -> int:
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ans = 0
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n = len(board)
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n = n - 1
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length = n + 1
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que = [(1,0)]
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idx = 0
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flag = [0 for i in range((n+1)*(n+1))]
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def add_node(que, idx, node):
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if len(que) <= idx:
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que.append(node)
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else:
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que[idx] = node
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def move(idx):
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row = 0
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column = idx % (n + 1)
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if idx % (n + 1) == 0: row -= 1
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row += idx // (n + 1)
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row = n - row
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oe = idx // (n + 1) % 2
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if idx % (n + 1) == 0: oe = 1 - oe
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if column == 0: column = n + 1
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column -= 1
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if oe == 1: column = n - column
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return (row, column)
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front = 0
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while idx - front >= 0:
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node = que[front]
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front += 1
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step = node[1]
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cur_loc = node[0]
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if flag[cur_loc] == 1: continue
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flag[cur_loc] = 1
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if cur_loc + 6 >= length * length:
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return step + 1
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for i in range(1, 7):
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(row, column) = move(i + cur_loc)
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if board[row][column]!= -1:
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if board[row][column] == length * length: return step + 1
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idx += 1
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add_node(que, idx, (board[row][column], step + 1))
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else:
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idx += 1
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add_node(que, idx, (i + cur_loc, step + 1))
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return -1
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