题解 | 迷宫寻路

n , m = map(int,input().split())
arr = []
for i in range(n):
    arr.append(list(input()))
graph = {}
for i in range(n):
    for j in range(m):
        if arr[i][j] == ".":
            graph[(i,j)] = []
            if i - 1 >= 0 and arr[i-1][j]==".":
                graph[(i,j)].append((i-1,j))
            if j - 1 >= 0 and arr[i][j-1]==".":
                graph[(i,j)].append((i,j-1))
            if j + 1 <= m - 1 and arr[i][j+1]==".":
                graph[(i,j)].append((i,j+1))
            if i + 1 <= n - 1 and arr[i+1][j]==".":
                graph[(i,j)].append((i+1,j))
# print(graph)
def can_reach(graph, start, target):
    stack = [start]
    visited = set()
    while stack:
        current = stack.pop()
        if current == target:
            return "Yes"
        if current in visited:
            continue
        visited.add(current)
        for neighbor in graph[current]:
            if neighbor not in visited:
                stack.append(neighbor)
    return "No"
print(can_reach(graph,(0,0),(n-1,m-1)))