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elmliu
V2EX  ›  Python

关于 Python 递归时修改全局变量失败的问题

  •  
  •   elmliu · 2018-09-23 18:07:12 +08:00 · 1522 次点击
    这是一个创建于 2257 天前的主题,其中的信息可能已经有所发展或是发生改变。
    def dfs_maze(path, target):
    global paths
    maze = [[" ","#","#"," "," "],[" "," "," ","#"," "],["#"," "," ","#"," "],[" "," "," ","#","#"],[" "," "," "," "," "]]

    if path[-1] == target:
    paths.append(path)
    print(path)
    return
    for each in [[0,1], [0,-1], [1, 0], [-1, 0]]:
    node = [path[-1][0] + each[0], path[-1][1] + each[1]]
    if -1 not in node and 5 not in node and node not in path and maze[node[0]][node[1]] != '#':
    path.append(node)
    dfs_maze(path, target)
    path.pop(-1)

    def main():
    dfs_maze([[0,0]], [4, 4])

    for each in paths:
    print(each)
    paths = []
    main()

    就是一个深搜解决迷宫最短路径的函数,path 是一个二维数组,储存已经走过的每一个点,target 是终点。在边界条件满足时,打印出来的路径是没问题的。但在深搜结束后,打印出来的 paths 是一堆[[0,0]]的二维数组,这是为何?
    不知为啥没有代码排版,sorry...
    Philippa
        1
    Philippa  
       2018-09-23 18:25:03 +08:00
    从新弄一个在线的 playground 版本的代码吧,尤其 Python 这种依赖缩进语言,10 个人有 9.99 个没耐心看这种没排版的代码。随手一搜,比如这个: https://www.katacoda.com/courses/python/playground
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