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maze_search.py
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'''
Find shortest path from top left column to the right lowest column using DFS.
only step on the columns whose value is 1
if there is no path, it returns -1
(The first column(top left column) is not included in the answer.)
Ex 1)
If maze is
[[1,0,1,1,1,1],
[1,0,1,0,1,0],
[1,0,1,0,1,1],
[1,1,1,0,1,1]],
the answer is: 14
Ex 2)
If maze is
[[1,0,0],
[0,1,1],
[0,1,1]],
the answer is: -1
'''
def find_path(maze):
cnt = dfs(maze, 0, 0, 0, -1)
return cnt
def dfs(maze, i, j, depth, cnt):
directions = [(0, -1), (0, 1), (-1, 0), (1, 0)]
row = len(maze)
col = len(maze[0])
if i == row - 1 and j == col - 1:
if cnt == -1:
cnt = depth
else:
if cnt > depth:
cnt = depth
return cnt
maze[i][j] = 0
for k in range(len(directions)):
nx_i = i + directions[k][0]
nx_j = j + directions[k][1]
if nx_i >= 0 and nx_i < row and nx_j >= 0 and nx_j < col:
if maze[nx_i][nx_j] == 1:
cnt = dfs(maze, nx_i, nx_j, depth + 1, cnt)
maze[i][j] = 1
return cnt