simplify-path.py

# -*- coding:utf-8 -*-


# Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.
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# In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix
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# Note that the returned canonical path must always begin with a slash /, and there must be only a single slash / between two directory names. The last directory name (if it exists) must not end with a trailing /. Also, the canonical path must be the shortest string representing the absolute path.
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# Example 1:
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# Input: "/home/"
# Output: "/home"
# Explanation: Note that there is no trailing slash after the last directory name.
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# Example 2:
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# Input: "/../"
# Output: "/"
# Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
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# Example 3:
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# Input: "/home//foo/"
# Output: "/home/foo"
# Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.
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# Example 4:
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# Input: "/a/./b/../../c/"
# Output: "/c"
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# Example 5:
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# Input: "/a/../../b/../c//.//"
# Output: "/c"
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# Example 6:
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# Input: "/a//b////c/d//././/.."
# Output: "/a/b/c"
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class Solution(object):
    def simplifyPath(self, path):
        """
        :type path: str
        :rtype: str
        """
        # 思路：
        # 1. split / 形成List
        # 2. 如果 .. 就　pop 前面的
        # 3. 还要考虑　'///' '/...'
        places = [p for p in path.split("/") if p!="." and p!=""]
        stack = []
        for p in places:
            if p == "..":
                if len(stack) > 0:
                    stack.pop()
            else:
                stack.append(p)
        return "/" + "/".join(stack)